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J
Electrical circuits
Unit guide
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This unit builds on:
t
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ideas introduced in unit 6G Changing circuits and unit 4F Circuits and conductors in the key stage 2
scheme of work.
^ _
ET ET
TY PC
G
K
Where this unit fits in
Prior learning
To make good progress, pupils starting this unit
need to:
• know that a complete circuit is required for
electrical devices to work
• be able to connect a circuit, draw and
interpret standard electrical symbols for
connection, cell/battery, lamp and switch.
➞ Transition quiz for unit J
The concepts in this unit are:
• Energy transfer in electric circuits.
• The abstract concept of current.
This unit leads onto:
unit 8J Magnets and electromagnets and unit 9I Energy and electricity.
Framework yearly teaching objectives – Energy
Use a simple model of energy transfer to explain:
• the purpose of cells in an electrical circuit
• that electric current carries energy to components in an electrical circuit
• that energy is transferred to components in both series and parallel circuits.
Expectations from the QCA Scheme of Work
At the end of this unit …
… most pupils will …
… some pupils will not have made so
much progress and will …
… some pupils will have
progressed further and will …
in terms of scientific enquiry NC Programme of Study Sc1 1a, b, c; 2c, g, i, j, k, l, m
• select and use appropriate equipment to investigate circuits
• measure current
• identify patterns in their results and draw conclusions
about series and parallel circuits
• know about the early ideas to do with the development
of the light bulb
• describe hazards associated with electricity and how to
deal with them.
• explore circuits using appropriate equipment
• identify patterns in their results and use these to
describe the behaviour of a simple circuit
• begin to understand how early ideas
contributed to the development of the light
bulb
• identify and report on hazards associated
with electricity.
• plan and carry out a systematic
investigation of series and parallel
circuits to obtain sufficient
evidence to draw conclusion
• give examples of the development
of scientific ideas about electricity
• explain how electricity can be
hazardous to humans.
in terms of physical processes NC Programme of Study Sc4 1a, b, c
• construct a range of working electrical circuits and
represent these in circuit diagrams
• state that electric current is the same at all points in a
series circuit and divides along the branches of a
parallel circuit
• use a flow model to describe resistance and to
distinguish between electric current and energy transfer
in a circuit
• compare and contrast the advantages of series and
parallel circuits in use.
• construct simple electrical circuits and
represent these diagrammatically
• give examples of useful circuits
• state safety rules for use of electricity.
• relate voltage of cells and
batteries qualitatively to energy
transfer in circuits
• use a flow model to explain the
difference between electric
current and energy transfer
• apply the idea that nerves are
electrical conductors to explain
electrical hazards.
Suggested lesson allocation (see individual lesson planning guides)
Direct route
J1
Electrical
energy
J2
Current affairs
J3
Different
circuits
J4
Models of electricity: Think
about models of electricity
J5
Electrical
hazards
Extra lessons (not in pupil book)
Review and assess progress
(distributed appropriately)
Additional information
This unit applies the concept of energy to electrical circuits.
Misconceptions
Pupils may think that electric current is some sort of power that makes things go and that current gets used up or burnt up by a bulb. Pupils may think
that current flows out of both terminals of a battery and it meets with a clash in the bulb causing light. Some may think that current travels round a
circuit from the battery getting used up as it goes round and so there is less current at the end of the circuit.
It is important that pupils distinguish between two abstract concepts: electricity as ‘flowing stuff’ and electrical energy as something that is
identified by input and output effects. Its effects are associated with the brightness of bulbs and its origins in the voltage rating of batteries. There
are necessary simplifications in the treatment, as appropriate to this early unit. Some pupils will confuse current and voltage.
Links with other areas of science and across the curriculum
Numeracy: Solving problems, using data. Citizenship: Electrical hazards. Technology: Control systems.
Health and safety (see activity notes to inform risk assessment)
Pupils must work with low voltages and under no circumstances experiment with mains electricity.
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Electrical energy
J1
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Lesson planning
guide
Learning objectives
i
ii
iii
Electricity carries energy to components in an electrical circuit.
A cell stores energy and a cell with a higher voltage stores more energy than one with lower voltage.
More than one cell connected together in a circuit is called a battery.
Scientific enquiry
^ _
iv
Test and make predictions about circuits. (Framework YTO Sc1 7b)
UG
Suggested alternative starter activities (5–10 minutes)
Introduce the unit
Share learning objectives
Problem solving
Capture interest (1)
Capture interest (2)
Demo that electricity
can flow through the
body and discussion
of electrical safety
issues.
• Find out how energy is transferred to
an electrical circuit.
• Find out that cells have different
voltages.
• Be able to test and make predictions
about circuits. (Sc1)
Groups of pupils
complete the circuit
in one of four
circuits.
Connect cells together
positive to negative.
Show a video clip of
safety precautions when
using electricity.
Catalyst Interactive
Presentations 1
Suggested alternative main activities
Activity
Learning
objectives
see above
Description
Approx.
timing
Target group
C
H
E
S
Textbook J1
i, ii and iii
Teacher-led explanation and questioning OR pupils work individually,
in pairs or in small groups through the in-text questions and then
onto the end-of-spread questions if time allows.
25 min
R/G
G
R
S
Activity J1a
Practical
i, ii and iv
Energy changes Pupils connect cells and switches to motors, lamps,
steel wool; and note energy transfers.
10 min
✓
Activity J1b
Paper
iv
Switch on! Pupils work in pairs to predict from circuit diagrams what
happens when switches are open and closed. This is a review from
KS2 activity.
15 min
Activity J1c
Catalyst Interactive
Presentations 1
iv
Support activity for pupils to work out from circuit animations what
happens when switches are open and closed.
20 min
✓
✓
✓
✓
Suggested alternative plenary activities (5–10 minutes)
Review learning
Sharing responses
Group feedback
Brainstorming
Looking ahead
Pupils describe how a
circuit works.
Whole-class discussion of responses
on energy transfers in Activity J1a.
Groups of pupils compare and
discuss their answers from
Activity J1b.
Will it, won’t it?
Pupils suggest what life would
be like with no electricity.
Learning outcomes
Most pupils will …
Some pupils, making less progress will …
Some pupils, making more progress will …
• understand that cells and batteries
provide electrical energy
• know that electricity is what carries
energy to make things work, e.g. for a
lamp to light
• be able to represent circuits using
symbols and make and test predictions
about circuits.
• identify what can go wrong in a simple circuit
and that a complete circuit is needed for a
lamp to light up
• know that electricity is what carries energy to
make things work, e.g. for a lamp to light.
• be able to solve puzzles of circuit diagrams with
multiple switches.
Key words
cells, chemical energy, volts, energy, complete circuit, battery, red only: electrical energy,
voltage
© Harcourt Education Ltd 2003 Catalyst 1
This worksheet may have been altered from the original on the CD-ROM.
Out-of-lesson learning
Homework J1
Textbook J1 end-of-spread questions
Sheet 1 of 1
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Print current page (1 page)
Current affairs
J2
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UG
Lesson planning
guide
Learning objectives
i
ii
iii
The difference between energy and electric current in a circuit.
Current is not used up in a circuit.
Changing the number of cells in a circuit affects current.
Scientific enquiry
iv
v
vi
vii
Use an ammeter to measure current. (Framework YTO Sc1 7d)
Make predictions about current. (Framework YTO Sc1 7b)
Present and interpret experimental results through routine use of tables. (Framework YTO Sc1 7f)
Model current in a variety of ways. (Framework YTO Sc1 7a, h)
Suggested alternative starter activities (5–10 minutes)
Recap last lesson
Share learning objectives
Word game
Brain storming
Capture interest
Demo that electricity
can flow through the
body from J1.
Or Unit map for
Electrical circuits.
• Find out what current is and measure it.
• Investigate how changing the components
in a circuit affects the current.
• Be able to make predictions about current.
(Sc1)
Play a quick game
of hangman with
the whole class
using words from
the unit.
Recap ways of
changing the
brightness of a
lamp.
Show a simulation to explore
ideas about current and an
animated water pipe analogy.
Catalyst Interactive
Presentations 1
Suggested alternative main activities
Activity
Learning
objectives
see above
Description
Approx.
timing
Target group
C
H
E
S
Textbook J2
i, ii, iii and
vii
Teacher-led explanation and questioning OR pupils work individually,
in pairs or in small groups through the in-text questions and then
onto the end-of-spread questions if time allows.
25 min
R/G
G
R
S
Activity J2a
Practical
ii, iv and vi
All the way round Pupils find out how electric current varies round a
simple circuit.
20 min
✓
Activity J2b
Practical
iii, iv and v
Brighter and dimmer Pupils work in groups to find out how to
change how brightly a bulb shines.
25 min
✓
✓
Activity J2c
Practical
iii, iv, v and
vi
Investigating electric current Pupils find out how the current
changes when the number of cells or bulbs in the circuit changes.
25 min
✓
(✓)
✓
Activity J2d
Catalyst Interactive
Presentations 1
iii and iv
Pupils find out how the current changes when the number of cells or
bulbs in the circuit changes.
25 min
✓
✓
✓
Activity J2e
Catalyst Interactive
Presentations 1
ii
ICT support version of Activity J2a.
✓
✓
Suggested alternative plenary activities (5–10 minutes)
Review learning
Sharing responses
Group feedback
Word game
Looking ahead
How to measure current
in an electrical circuit.
Whole-class discussion of
responses from Activity J2a.
Groups of pupils compare and discuss
their answers from Activity J2b.
Pupils discuss
word pairs.
Ask pupils to suggest alternative
ways of connecting components.
Learning outcomes
Most pupils will …
Some pupils, making less progress will …
Some pupils, making more progress will …
• describe how electrical energy is
transferred to components in a circuit
when a current flows
• be able to construct circuits and
measure current using an ammeter
• be able to show how current is not used
up in a circuit.
• begin to understand the idea of current as
electricity flowing in wires
• see that current is not used up in a circuit by
making measurements with an ammeter.
• explain the relationship between the number of
cells/batteries in a circuit or the number of
lamps and the size of the current.
Key words
current, ammeter, amps
© Harcourt Education Ltd 2003 Catalyst 1
This worksheet may have been altered from the original on the CD-ROM.
Out-of-lesson learning
Homework J2
Textbook J2 end-of-spread questions
Sheet 1 of 1
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Print current page (1 page)
Different circuits
J3
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UG
Lesson planning
guide
Learning objectives
i
ii
iii
The electric current is the same at all points in a series circuit.
Current divides along the branches of a parallel circuit.
Design and construct series and parallel circuits.
Scientific enquiry
iv
v
vi
Use a model to understand current, resistance and series/parallel circuits. (Framework YTO Sc1 7a, h)
Consider early scientific ideas, including how experimental evidence and creative thinking have been combined to provide scientific explanations.
(Framework YTO Sc1 7a) (red only)
Describe and explain what results show when drawing conclusions; begin to relate conclusions to scientific knowledge and understanding.
(Framework YTO Sc1 7g)
Suggested alternative starter activities (5–10 minutes)
Recap last lesson
Share learning objectives
Problem solving
Capture interest (1)
Capture interest (2)
Pupils look at several
circuit diagrams and
say what the reading
is on each ammeter.
• Find out about series and
parallel circuits.
• Be able to use a water pipe
model of electricity. (Sc1)
Demo of circuit with
different lengths of
pencil lead.
Show a simulation to illustrate series
and parallel circuits with the water
pipe analogy.
Catalyst Interactive Presentations 1
Set up a simple series
and parallel circuit and
ask how they are
different.
Suggested alternative main activities
Activity
Learning
objectives
see above
Description
Approx. Target group
timing
C
H
E
S
Textbook J3
i, ii, iii and
iv
Teacher-led explanation and questioning OR pupils work individually, in
pairs or in small groups through the in-text questions and then onto the
end-of-spread questions if time allows.
25 min
R/G
S
Activity J3a
Practical
ii, iii, vi
and vii
Parallel circuits Pupils work in groups to set up their own parallel
circuits and measure the current at three points.
25 min
✓
✓
Activity J3b
Practical
ii, iii and vi
Lighting circuits Pupils design a circuit with two light bulbs that both
light brightly.
25 min
✓
✓
Activity J3c
Paper
v
Developing the light bulb Pupils study the biographies of three of the
scientists involved in developing the electric filament lamp.
20 min
Activity J3d
Catalyst Interactive
Presentations 1
ii, iii and vi
This simulation is based on Activity J3b. Pupils can be asked to
investigate closing switches.
10 min
✓
✓
✓
✓
Activity J3e
Catalyst Interactive
Presentations 1
vi
To illustrate series and parallel circuits using water pipe model.
10 min
✓
✓
✓
✓
G
R
✓
Suggested alternative plenary activities (5–10 minutes)
Review learning
Sharing responses
Group feedback
Word game
Looking ahead
Pupils describe current
flow in series and
parallel circuits.
Whole-class discussion of
conclusions from Activity
J3a.
Groups of pupils compare and
discuss their solutions from
Activity J3b.
To check progress
pupils play dominoes
about electricity.
Pupils suggest strengths and
limitations of water flow model of
current flow.
Learning outcomes
Most pupils will …
Some pupils, making less progress will …
Some pupils, making more progress will …
• use a simple analogy to understand the
idea of resistance and that resistance
makes it hard for the current to flow
• understand how the electric current is
the same at all points in a series circuit
and current divides along the branches
of a parallel circuit
• be able to use a water pipe analogy to
understand series and parallel circuits.
• understand that resistance makes it hard for
the current to flow
• apply their understanding of circuits to
understand how a series and parallel circuit are
different.
• describe how resistance is used in dimmer
switches and fuses
• be able to design and construct series and
parallel circuits and explain the limitations to the
water model.
Key words
resistance, series circuits, parallel circuit, red only: filament
Out-of-lesson learning
Homework J3. Textbook J3 end-of-spread questions
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Print current page (1 page)
Models of electricity – Think
about models of electricity
J4
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Lesson planning
guide
Learning objectives
The structure of this lesson is based around the CASE approach. The starter activities give concrete preparation. The lesson then moves away from the
concrete towards a challenging situation, where pupils need to think. The plenary activities give pupils time to discuss what they have learnt, to commit
their understanding to paper and express their ideas verbally to the rest of the class.
Scientific enquiry
i
ii
Use creative thinking to understand several models of electricity. (Framework YTO Sc1 7a)
Evaluate the usefulness and limitations of models. (Framework YTO Sc1 7h)
UG
Suggested alternative starter activities (5–10 minutes)
Bridging to the unit
Setting the context
Concrete preparation (1)
Concrete preparation (2)
Discuss the need for a model to
explain electricity and current.
Look at a model village or model
human body and compare it with the
real thing.
Show a simulation to illustrate the coal
truck model.
Catalyst Interactive Presentations 1
Set up a model railway.
Suggested main activities
Activity
Learning
objectives
see above
Description
Approx.
timing
Target group
C
H
E
S
Textbook J4
i and ii
Teacher-led explanation and questioning OR pupils work individually, in
pairs or in small groups through the in-text questions and then onto
the end-of-spread questions if time allows.
25 min
R/G
G
R
S
Activity J4a
Discussion
i and ii
‘Class and matches’ model Pupils stand in a circle – all of the class is
involved in the model to give them experience of using models
(kinaesthetic).
10 min
✓
✓
✓
✓
Suggested alternative plenary activities (5–10 minutes)
Group feedback
Bridging to other topics
Pupils discuss how the different models helped them to understand
electricity better.
Pupils discuss how the use of scientific models will help them in other
topics.
Learning outcomes
Most pupils will …
Some pupils, making less progress will …
Some pupils, making more progress will …
• understand the difference between
energy and electric current in a circuit
• use a model to explain ideas about
electrical circuits appreciating that it
helps them to imagine what is
happening.
• apply a model to develop and consolidate their
understanding.
• be able to explain the strengths and weaknesses
of a model of electricity.
Key words
models
Out-of-lesson learning
Textbook J4 end-of-spread questions
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Electrical hazards
J5
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Lesson planning
guide
Learning objectives
i
ii
iii
Finding faults in a circuit.
Hazards of electricity for humans.
How fuses and ring mains work.
Scientific enquiry
iv
v
Use secondary sources of information and prepare presentations. (Framework YTO Sc1 8d)
Consider early scientific ideas, including how experimental evidence and creative thinking have been combined to provide scientific explanations.
(Framework YTO Sc1 7a)
Suggested alternative starter activities (5–10 minutes)
Recap last lesson
Share learning objectives
Problem solving (1)
Problem solving (2)
Capture interest
Recap the water pipe
analogy as a model
for series and
parallel circuits.
• Find out about hazards of
electricity for humans.
• Find out about fuses.
• Be able to present information
from research. (Sc1)
Pupils identify the electrical
hazards in a picture on the
pupil sheet.
Pupils find electrical
hazards in an
interactive tour.
Catalyst Interactive
Presentations 1
Demo that electricity
can flow through the
body.
Suggested alternative main activities
Activity
Learning
objectives
see above
Description
Approx.
timing
Target group
C
H
E
S
Textbook J5
i, ii and iii
Teacher-led explanation and questioning OR pupils work individually, in
pairs or in small groups through the in-text questions and then onto
the end-of-spead questions if time allows.
25 min
R/G
G
R
S
Activity J5a
Paper
i and iii
Christmas tree lights Designing new circuits comparing Xmas tree
lights and ring main model.
25 min
✓
Activity J5b
Practical
i and iii
The weakest link Pupils investigate how a fuse protects a circuit.
20 min
✓
Activity J5c
ICT
ii, iv and v
Discoveries in electricity Pupils work in small groups using secondary
sources to prepare PowerPoint presentations or leaflets on Galvani’s and
Volta’s work.
25 min
✓
Activity J5d
Catalyst Interactive
Presentations 1
i
Support activity on how a torch works – demonstrating and diagnosing
faults in it.
10 min
✓
✓
Suggested alternative plenary activities (5–10 minutes)
Review learning
Sharing responses
Group feedback
Word game
Looking ahead
Pupils summarise key
points about hazards and
electricity.
Whole-class discussion of
presentations from Activity
J5c.
Groups of pupils compare and
discuss their solutions from
Activity J5a.
Check progress by playing
‘bingo’ with key words
from the unit.
Pupils revise and
consolidate knowledge
from the unit.
Learning outcomes
Most pupils will …
Some pupils, making less progress will …
Some pupils, making more progress will …
• consider the hazards of electricity for
humans
• identify key points and sequence ideas
from secondary sources and prepare
presentations.
• identify hazards of electricity for humans and
state safety rules for use of electricity
• with help, e.g. a writing frame, sequence ideas
from secondary sources which they can
contribute to group presentations.
• apply the idea that nerves are electrical
conductors to explain electrical hazards.
Key words
fault, ring main, fuse
Out-of-lesson learning
Homework J5
Textbook J5 end-of-spread questions
Talk to adults about circuits in the home
© Harcourt Education Ltd 2003 Catalyst 1
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Sheet 1 of 1
6
Print current page (1 page)
J1
M
Electrical energy
Starters
Suggested alternative starter activities (5–10 minutes)
p
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Introduce the unit
Share learning
objectives
Problem solving
Capture interest (1)
Capture interest (2)
t
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Demo that electricity can
flow through the body
and discussion of
electrical safety issues.
● Find out how energy is
transferred to an
electrical circuit.
● Find out that cells have
different voltages.
● Be able to test and
make predictions about
circuits. (Sc1)
Groups of pupils complete
the circuit in one of four
circuits.
Connect cells together
positive to negative.
Show a video clip of safety
precautions when using
electricity.
Catalyst Interactive
Presentations 1
^ _
UG LP
Introduce the unit
● Using a 1.5 V battery and a microammeter, demonstrate the
three scenarios on the teacher sheet.
➔ Technician sheet
➔ Teacher sheet
● Explain that this shows that electricity can flow through the
body. The 240 V mains supply is 160 times higher than the
1.5 V battery. If electricity from the mains flowed through
the body, it could be enough to stop the heart beating.
● Make sure pupils understand that mains electricity is much
more dangerous than batteries, and that they must not
insert wires into electrical sockets. Stress that they must
never use mains electricity for experiments, and that with
water mains electricity is even more hazardous.
Share learning objectives
● Ask pupils to write a list of FAQs they would put on a
website telling people about energy from electricity. Collect
suggestions as a whole-class activity, steering pupils towards
those related to the objectives. Conclude by highlighting
the questions you want them to be able to answer at the end
of the lesson.
Problem solving
● Give groups of pupils one of the circuits described on the
technician sheet. Ask them to complete the circuit, and also
to be ready to report how they did this. Remind them that
batteries are safe but they should never use mains electricity
for experiments.
● When they have finished, choose a group to explain why
there was not a complete circuit. Ask which other groups
had the same problem. Discuss all four circuits in this way.
➔ Technician sheet
Expected outcomes
1 The lamp has a broken filament.
2 Both connections to the lamp are on
the same side.
3 The two batteries are different ways
around.
4 One wire is not connected.
Capture interest (1)
● Demonstrate that if using several cells, they need to be
connected together correctly. Show what happens when
they are wrongly connected using a circuit with a lamp.
Equipment
several cells, a lamp, connecting wires
Capture interest (2)
● Ask for pupils’ views about electrical safety before showing a
video clip of safety precautions when using electricity.
Conclude by saying that batteries are safe, but that they
must never use mains electricity for experiments and never
put wires in sockets. Emphasise that even professional
electricians sometimes make mistakes and are electrocuted.
© Harcourt Education Ltd 2003 Catalyst 1
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➔ Catalyst Interactive Presentations 1
Sheet 1 of 1
Print current page (1 page)
J1
M
p
Starters
Electrical energy
Introduce the unit
?
Technician sheet
Supply the following for a demonstration to show
that electric current will flow through the human
^ _ body:
UG LP
● a 1.5 V battery
● an ammeter that can be set to measure
TN
microamps
● three connecting wires.
t
6
u
A pupil will hold two connectors and a current of
about 2 or 3 µA will flow, which will rise with wet
hands.
pupil holds one
in each hand
1.5 V battery
© Harcourt Education Ltd 2003 Catalyst 1
This worksheet may have been altered from the original on the CD-ROM.
microammeter
Sheet 1 of 1
J1
Starters
Electrical energy
Introduce the unit
Teacher sheet
1 Without the battery connected, ask a pupil to
hold a probe from the ammeter in each hand.
Show that this gives a zero reading.
2 Connect the battery to the ammeter with one
wire. Ask the pupil to hold one probe from the
battery in contact with the palm of one hand,
and the second probe from the ammeter in
the other hand, as shown in the diagram. A
small current will register (about 2 or 3 µA).
3 Repeat this with wet hands to show that the
current goes up significantly.
© Harcourt Education Ltd 2003 Catalyst 1
This worksheet may have been altered from the original on the CD-ROM.
pupil holds one
in each hand
1.5 V battery
microammeter
Sheet 1 of 1
Print current page (1 page)
J1
M
Electrical energy
Starters
Problem solving
p
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Technician sheet
t
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Provide the following for each set of four circuits:
^ _
UG LP
TN
6
● a faulty lamp (filament broken)
● a spare bulb
● seven filament lamps (working)
● six batteries
● four switches
● 16 connecting wires.
Use the above equipment to make sets of the following four circuits,
labelled 1 to 4 (each group of pupils has circuit 1, 2, 3 or 4):
● circuit 1: a series circuit with a lamp and a battery, but the
filament of the lamp is broken
● circuit 2: a series circuit with a lamp and a battery, but the leads
are both attached to the same side of the lamp
● circuit 3: a series circuit with one lamp and two batteries, but one
of the batteries is the wrong way round
● circuit 4: a complicated spaghetti-like circuit with, say, five lamps
and two batteries, but one of the leads is not connected. The
circuit should be set up so that the leads look muddled.
© Harcourt Education Ltd 2003 Catalyst 1
This worksheet may have been altered from the original on the CD-ROM.
Sheet 1 of 1
6
Print current page (1 page)
J2
M
Current affairs
Starters
Suggested alternative starter activities (5–10 minutes)
p
?
Recap last lesson
Share learning
objectives
Word game
Brainstorming
Capture interest
t
u
Demo that electricity can
flow through the body
from J1.
Or Unit map for Electrical
circuits.
● Find out what current is
and measure it.
● Investigate how
changing the
components in a circuit
affects the current.
● Be able to make
predictions about
current. (Sc1)
Play a quick game of
hangman with the whole
class using words from the
unit.
Recap ways of changing
the brightness of a lamp.
Show a simulation to
explore ideas about current
and an animated water pipe
analogy.
Catalyst Interactive
Presentations 1
^ _
UG LP
Recap last lesson
● Either use the safety starter from Lesson J1 if it was not
used in the last lesson.
● Or draw the outline of the unit map on the board then
ask pupils to give you words to add, saying where to
add them. Suggest some words yourself when necessary
to keep pupils on the right track.
➔ Unit map
● Or give out the unit map and ask pupils to work in
groups deciding how to add the listed words to the
diagram. Then go through it on the board as each
group gives suggestions.
Share learning objectives
● Ask pupils to write a list of FAQs they would put on a
website telling people about electric current. Collect
suggestions as a whole-class activity, steering pupils
towards those related to the objectives. Conclude by
highlighting the questions you want them to be able to
answer at the end of the lesson.
Word game
● Play a game of hangman with the whole class to reinforce
vocabulary and spelling of these key words.
Key words
electrical energy, cell, complete circuit,
filament lamp, switch, volts, voltage,
battery, positive, negative, current,
ammeter, amps
Brainstorming
● Recap ways of changing the brightness of a lamp from
Key Stage 2: increase the number of batteries; use
connecting wire of lower resistance or shorter length;
possibly increase the voltage of the battery.
Equipment
a battery (1.5 V), a lamp (2.5 V or 3.5 V),
a switch, connecting wires, extra batteries
and wires
● Show pupils a series circuit with a dimly lit lamp. Ask
them how they could make it brighter. Give pupils a few
minutes to discuss this in groups then ask for feedback.
Capture interest
● Show a water pipe animation and ask pupils to imagine
swimming in a fast-flowing river. Follow the path of
the water on the screen and think about what happens
at junctions and at each point of the circuit. Then ask
them to imagine being in a flow of current.
➔ Catalyst Interactive Presentations 1
● Look at the electric circuit in the animation, discussing
what happens at junctions and at components. Match
up with analogous components in the water model.
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J
Unit map
Electrical circuits
M
p
?
t
u
^ _
Energy from
electricity
Current
Different
circuits
UG LP
TN
Electricity
Modelling
electricity
Electrical
hazards
Copy the unit map and use these words to help you complete it.
You may add words of your own too.
ammeter
amps, A
battery
cell
chemical energy
circuit symbols
class and matches model
coal truck model
complete circuit
electrical energy
fault
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filament R
fuse
parallel circuit
resistance
ring main
series circuit
switch
voltage
volts, V
water flow model
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6
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J3
M
Different circuits
Starters
Suggested alternative starter activities (5–10 minutes)
p
?
Recap last lesson
Share learning
objectives
Problem solving
Capture interest (1)
Capture interest (2)
t
u
Pupils look at several
circuit diagrams and say
what the reading is on
each ammeter.
● Find out about series
and parallel circuits.
● Be able to use a water
pipe model of
electricity. (Sc1)
Demo of circuit with
different lengths of pencil
lead.
Show a simulation to
illustrate series and
parallel circuits with the
water pipe analogy.
Catalyst Interactive
Presentations 1
Set up a simple series and
parallel circuit and ask how
they are different.
^ _
UG LP
Recap last lesson
● Give out the pupil sheet. As a whole-class activity, ask
individual pupils to say what the reading is on the
ammeters marked with a question mark.
➔ Pupil sheet
Answers
A 0.1 A, B 0.2 A, 0.2 A, C 0, D 0.3 A, E 0
Share learning objectives
● Ask pupils to write a list of FAQs they would put on a
website telling people about different kinds of electric
circuit. Collect suggestions as a whole-class activity,
steering pupils towards those related to the objectives.
Conclude by highlighting the questions you want them
to be able to answer at the end of the lesson.
Problem solving
● Show pupils a circuit with a battery, a lamp and two
crocodile clips positioned quite close together on a
length of pencil lead. Remind them of the Key Stage 2
experiment using different wires in a circuit like this.
➔ Technician sheet
● Ask pupils to predict what will happen to the lamp
when you move the crocodile clips further apart to
include a longer length of pencil lead in the circuit.
● Move the crocodile clips and discuss the effect. Was
their prediction correct?
Capture interest (1)
● Show a simulation to illustrate series and parallel
circuits with the water pipe analogy. Ask pupils what
the difference is between the two circuits.
➔ Catalyst Interactive Presentations 1
● Explain that there is more than one route around a
parallel circuit. Ask pupils to suggest the advantages of
this.
Capture interest (2)
● Set up a series circuit with two or three lamps, and a
parallel circuit with the same number of lamps. Use the
same voltage supply (batteries or low voltage supply)
for both and include a switch in each just before the
second lamp. Demonstrate the effect of the switch in
both circuits.
➔ Technician sheet
● Ask pupils to suggest differences between the circuits,
such as: the lamps in parallel are brighter; the switch
turns all the bulbs off in the series circuit but only one
in the parallel circuit.
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J3
M
Starters
Different circuits
Recap last lesson
p
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t
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circuit A
circuit B
^ _
UG LP
TN
A ?
A
0.1 A
A
0.2 A
A
?
A
?
circuit D
circuit C
0.3 A A
A ?
A
?
circuit E
A ?
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Different circuits
J3
M
Starters
Problem solving
p
?
Technician sheet
t
u
Provide the following for a demonstration:
^ _ ● a circuit with a battery or low voltage
supply connected to a lamp and two
wires ending in crocodile clips
UG LP
TN
● a length of pencil lead for the crocodile
clips to clip onto.
Check that the lamp brightness visibly
changes as the crocodile clips are
moved closer together or further apart
on the pencil lead, including a longer
or shorter length in the circuit.
crocodile clips
pencil
lead
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Sheet 1 of 1
J3
Different circuits
Starters
Capture interest (2)
Technician sheet
Provide the following for a demonstration, set up as shown in the circuit diagrams:
● six lamps in holders
● batteries or low voltage supply (the same for each circuit)
● two switches
● connecting wires.
series
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parallel
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J4
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^ _
Models of electricity – Think
about
Starters
Suggested alternative starter activities (5–10 minutes)
Bridging to the unit
Setting the context
Concrete preparation (1)
Concrete preparation (2)
Discuss the need for a model to
explain electricity and current.
Look at a model village or model
human body and compare it with
the real thing.
Show a simulation to illustrate
the coal truck model.
Catalyst Interactive
Presentations 1
Set up a model railway.
UG LP
Bridging to the unit
● Remind pupils that this unit considers electric circuits.
We can’t see inside a circuit so we need a model to help
us understand what is happening.
● Ask pupils what parts of the model might represent
(such as current and components). Establish that it
must explain what happens.
Setting the context
● Look at a model village or a model human body.
● For the model village, discuss the advantages, such as
allowing you to look down on the whole area and get
an overview of where everything is. Ask pupils whether
a model of the school would have helped them to find
their way around when they first arrived. Think of
limitations of the model, such as: it’s too small for us to
see inside buildings; it may go out of date if the real
landscape or building changes.
Equipment
a model village, a model human body or
another model such as a ship
● For the model of a human body (or part), discuss the
advantages, such as: there is no blood; you can see all
the body parts just by getting it out of cupboard; you
don’t need to cut open a real body; it’s 3D. Think of
limitations, such as: there is no blood; colours and
textures are not represented; people are not all
identical; it doesn’t allow you to look inside organs;
you can’t put it under a microscope to see cells.
Concrete preparation (1)
● Show pupils a coal truck model simulation and discuss
what they think each part might represent in an
electrical circuit.
➔ Catalyst Interactive Presentations 1
Concrete preparation (2)
● Set up a model railway with a train pulling some empty
trucks around a loop of track. Have a point where
trucks can load and a point where they can unload,
preferably without stopping (such as with chutes or
tipping trucks).
Equipment
a model railway circuit
● Discuss what each part of the model might represent in
an electric circuit. Explain the significance of the
loading/unloading points (where the trucks collect and
give up energy).
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J5
M
Electrical hazards
Starters
Suggested alternative starter activities (5–10 minutes)
p
?
Recap last lesson
Share learning
objectives
Problem solving (1)
Problem solving (2)
Capture interest
t
u
Recap the water pipe
analogy as a model for
series and parallel
circuits.
Catalyst Interactive
Presentations 1
● Find out about hazards
of electricity for humans.
● Find out about fuses.
● Be able to present
information from
research. (Sc1)
Pupils identify the
electrical hazards in a
picture on the pupil sheet.
Pupils find electrical
hazards in an interactive
tour.
Catalyst Interactive
Presentations 1
Demo that electricity can
flow through the body.
^ _
UG LP
Recap last lesson
● Explain to pupils that in the water pipe analogy, the
flow of water through the pipe represents the flow of
current around a circuit. The flow must be the same
everywhere unless extra water is added or water is lost.
Elicit that a water wheel represents a component that
converts electrical energy to some other form of energy.
➔ Catalyst Interactive Presentations 1
● When the water comes to a junction of two pipes it will
split, some flowing through one and some through the
other. The total amount of water will stay the same. If
the two pipes are identical then the same amount of
water will flow through each. Ask whether it is easier
for water to flow through a thick pipe or a thin one.
Share learning objectives
● Ask pupils to write a list of FAQs they would put on a
website telling people about faults and hazards in
electrical circuits. Collect suggestions as a whole-class
activity, steering pupils towards those related to the
objectives. Conclude by highlighting the questions you
want them to be able to answer at the end of the lesson.
Problem solving (1)
● Ask pupils to work in pairs or small groups to identify
the electrical hazards in the picture on the pupil sheet.
➔ Pupil sheet
● Bring the class together and ask individual groups for
hazards they spotted. Build up a list on the board.
Problem solving (2)
● Show an interactive tour around the house. Ask
individual pupils to come up and click on the electrical
hazard in each room. If they are correct, the hazard is
explained. A score of correct identifications is given at
the end, which can be discussed with the class.
➔ Catalyst Interactive Presentations 1
● Put a broken bulb in the gap to show that if one bulb
blows, all the lights go out.
Capture interest
● Repeat the safety demo from Lesson J1 or J2. This
allows different pupils to be part of the demo, and now
also gives opportunities for reading the meter.
➔ Technician sheet
➔ Teacher sheet
● Explain that mains appliances are carefully designed
with good electrical insulation to prevent users coming
into contact with the wires. Even so, they should not
be used with wet hands.
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J5
M
Electrical hazards
6
Starters
Problem solving (1)
p
?
t
u
Spot the electrical hazards.
^ _
UG LP
TN
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Energy changes
J1a
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^ _
UG LP
Teacher
activity notes
Type
Purpose
Differentiation
Practical
Pupils build circuits with lamps, motors and wire wool to see a variety of energy outputs,
to link with energy in Unit I.
Core, Help
Running the activity
Pupils work in groups, ideally with each group working through the whole activity.
If there is a shortage of components, groups could be collected into threes, with each
group testing one component only.
you think pupils will not be able to melt the wire wool sensibly and safely,
TC If
demonstrate this part of the experiment. Alternatively, it may be wise to keep the
wire wool supply and give a few strands to each group as they are ready for it.
Pupils may need to find the fault if their circuit does not work. Guide them through
the process of checking all connections, trying different lamps and finally trying
different cells.
Core: Instructions are given for connecting up the circuits and the headings are
provided for pupils to make their own results table.
Help: This provides a results table and structured questions. The sheet may be given
to pupils in addition to the Core sheet for them to fill in their results rather than
making their own results table.
Expected outcomes
Pupils discover that they need a complete circuit before anything happens. The
lamp brightness is independent of which way round the wires are connected, but
the motor reverses. They should see that fewer cells results in a lower energy output
as shown by a dimmer lamp and a slower motor.
The wire wool burns through, and this breaks the circuit.
Pitfalls
If you are using standard dry cells, then beware those that are ‘flat’. Note that they
cannot be checked with a voltmeter, only across a lamp. Also wires sometimes
fracture inside the insulation. It is wise to have a tray for faulty components, so that
they do not go back into stock. It is good practice to encourage pupils to disconnect
cells when they are not using the circuits, to help them last longer.
The wire wool activity is popular, but it runs down the cells quickly, so do not allow
pupils to carry it on for too long.
Safety notes
Eye protection should be worn. The wire wool sparks. Warn pupils that wire wool
has sharp strands. They often penetrate the skin to leave behind minute metal
‘splinters’.
Answers
Core and Help:
Device
Types of energy it
gives out
Effect of swapping
the wires
Effect of changing the
number of cells
lamp
light and heat
no change
Fewer cells make the
lamp dimmer.
motor
movement/kinetic, The motor direction
sound, heat
reverses.
wire wool
light and heat
Fewer cells make the
motor slower.
1 The results are variable.
2 The results are variable.
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Energy changes
J1a
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^ _
Technician
activity notes
Type
Purpose
Differentiation
Practical
Pupils build circuits with lamps, motors and wire wool to see a variety of energy outputs,
to link with energy in Unit I.
Core, Help
Equipment
For each group:
UG LP ● four 1.5 V cells in holder
TN
●
●
●
●
●
●
●
three connecting wires
a 6 V lamp in holder
a 6 V motor in holder
a switch
a few strands of wire wool
a pair crocodile clips
a heatproof mat.
For your information
Running the activity
Pupils work in groups, ideally with each group working through the whole
activity. If there is a shortage of components, groups could be collected into
threes, with each group testing one component only.
If you think pupils will not be able to melt the wire wool sensibly and safely,
demonstrate this part of the experiment. Alternatively, it may be wise to keep the
wire wool supply and give a few strands to each group as they are ready for it.
Pupils may need help to find the fault if their circuit does not work. Guide them
through the process of checking all connections, trying different lamps and
finally trying different cells
Core: Instructions are given for connecting up the circuits and the headings are
provided for pupils to make their own results table.
Help: This provides a results table and structured questions. The sheet may be
given to pupils in addition to the Core sheet for them to fill in their results rather
than making their own results table.
Expected outcomes
Pupils discover that they need a complete circuit before anything happens. The
lamp brightness is independent of which way round the wires are connected, but
the motor reverses. They should see that fewer cells results in a lower energy
output as shown by a dimmer lamp and a slower motor.
The wire wool burns through, and this breaks the circuit.
Pitfalls
If you are using standard dry cells, then beware those that are ‘flat’. Note that they
cannot be checked with a voltmeter, only across a lamp. Also wires sometimes
fracture inside the insulation. It is wise to have a tray for faulty components, so
that they do not go back into stock. It is good practice to encourage pupils to
disconnect cells when they are not using the circuits, to help them last longer.
The wire wool activity is popular, but it runs down the cells quickly, so do not
allow pupils to carry it on for too long.
Safety notes
Eye protection should be worn. The wire wool sparks. Warn pupils that wire wool
has sharp strands. They often penetrate the skin to leave behind minute metal
‘splinters’.
© Harcourt Education Ltd 2003 Catalyst 1
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Energy changes
J1a
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^ _
UG LP
TN TC
Activity
Core
You are going to connect up some circuits to see electrical
energy changing to other forms of energy.
Wear eye
protection.
Wire wool has
sharp strands
– take care not to
cut yourself. When
you switch on the
circuit, make sure
you are not touching
the wire wool.
!
Obtaining evidence
1
Make a table like the one below to record your results. Your
teacher may give you a table to fill in.
Device Types of energy Effect of swapping
it gives out
the wires
Effect of changing
the number of cells
lamp
2
3
4
5
6
7
8
9
Connect a battery of four cells to a
ⴙ
ⴚ
ⴙ
lamp and switch as shown in the
diagram.
Switch on. Complete the first two
spaces in your table for the lamp.
Switch off and swap over the wires to
the lamp so that they go to the
opposite sides.
Switch on and record what happens in your table.
Take out one of the cells to leave three in the circuit.
Switch on, then repeat with two cells and then one cell.
Record what happens in your table.
Repeat steps 2 to 6 using a motor
instead of the lamp.
ⴙ
ⴚ
ⴙ
Put some strands of wire wool on a
heatproof mat. Using crocodile
clips, connect a battery of four
cells to the wire wool as shown.
Switch on. Complete the first
motor
space in your table for
the wire wool.
1 What happens if you change how
many strands of wire wool you use?
2 What happens if you move the
crocodile clips closer together?
© Harcourt Education Ltd 2003 Catalyst 1
This worksheet may have been altered from the original on the CD-ROM.
ⴙ
ⴚ
wire wool
ⴙ
ⴚ
ⴙ
ⴚ
ⴙ
ⴚ
Remember
to switch off the
circuit before you
make any
changes.
ⴚ
ⴙ
ⴚ
ⴙ
ⴚ
ⴚ
ⴙ
ⴚ
ⴙ
ⴚ
heat proof
mat
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Energy changes
J1a
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Presenting the results
p
?
Record your results in this table.
t
u
The first row has been partly filled in for you.
Activity
Help
^ _
UG LP
TN TC
Device
Types of energy
it gives out
Effect of swapping
the wires
Effect of changing
the number of cells
lamp
light and heat
When I swapped the wires
over, the lamp
When I used three cells,
the lamp was
...............................................................
...............................................................
...............................................................
...............................................................
...............................................................
...............................................................
...............................................................
...............................................................
...............................................................
...............................................................
motor
wire
wool
1 Investigate what happens when you change the number of strands of wire wool.
2 Investigate what happens when you move the crocodile clips closer together.
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Switch on!
J1b
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^ _
UG LP
Teacher
activity notes
Type
Purpose
Differentiation
Paper
Pupils gain experience of problem solving in the context of circuits.
Core
Running the activity
Pupils work individually or in pairs to work out what happens in the circuits on
the sheet when the switches are open and closed. This reinforces the knowledge
that a complete circuit is needed for a lamp to light.
The circuits are straightforward parallel circuits. A table is provided for pupils to
copy and complete. If preferred, the sheet could be used as a write-on disposable
sheet, with the pupils instructed to write in the table on the sheet.
Answers
1 A, C
2 A, B, C
3 none
4 D, E, F
5
Switches closed
Lamps lit
1
none
2
G
3
none
4
none
1, 2
G
1, 3
H
1, 4
none
2, 3
G
2, 4
G
3, 4
I
1, 2, 3
G, H
1, 3, 4
H, I
2, 3, 4
G, I
1, 2, 3, 4
G, H, I
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J1b
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Activity
Core
Switch on!
You are going to look at some circuit diagrams and work out
what happens when the switches are opened and closed.
^ _
UG LP
TN
F
C
E
B
D
A
circuit 2
circuit 1
Switches closed
H
lamps lit
1
G
1
2
2
3
3
4
I
1, 2
4
circuit 3
1, 3
1, 4
2, 3
2, 4
1 Which lamps are lit in circuit 1?
2 Which lamps will be lit in circuit 1 if you
close the switch?
3 Which lamps are lit in circuit 2?
4 Which lamps will be lit in circuit 2 if you
close the switch?
5 Copy and complete the table opposite
for circuit 3.
© Harcourt Education Ltd 2003 Catalyst 1
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3, 4
1, 2, 3
1, 3, 4
2, 3, 4
1, 2, 3, 4
Circuit 3
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All the way round
J2a
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^ _
UG LP
Teacher
activity notes
Type
Purpose
Differentiation
Practical (or demonstration)
Pupils learn how to connect and use ammeters and measure electric current with them.
They show that the current is the same all the way round a circuit.
Core
Running the activity
The activity sheet suggests a group practical. The teacher may prefer to
demonstrate the circuit, in which case there will be sufficient meters to place
them in each position in the circuit, instead of moving them.
TC The sheet provides a results table for pupils to copy, and instructions to build the
circuit and record the ammeter reading at three positions in the circuit.
Other relevant material
Skill sheet 17: Reading an ammeter
Expected outcomes
The electric current is the same at every point in the circuit.
Pitfalls
If you are using standard dry cells, then beware those that are ‘flat’. Note that
they cannot be checked with a voltmeter, only across a lamp. Also wires
sometimes fracture inside the insulation. It is wise to have a tray for faulty
components, so that they do not go back into stock. It is good practice to
encourage pupils to disconnect cells when they are not using the circuits, to help
them last longer.
If analogue meters are used, they must be checked beforehand to ensure that they
will read the same current. Pupils may be concerned when ammeters give
negative readings. Remind them to swap the wires.
Answers
1 The electric current is the same all the way round the circuit.
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All the way round
J2a
M
p
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t
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^ _
UG LP
TN
Technician
activity notes
Type
Purpose
Differentiation
Practical (or demonstration)
Pupils learn how to connect and use ammeters and measure electric current with them.
They show that the current is the same all the way round a circuit.
Core
Other relevant material
Skill sheet 17: Reading an ammeter
Equipment
For each group:
●
●
●
●
●
two 1.5 V cells in holder
five connecting wires
two 2.5 V lamps in holders
a switch
a DC ammeter (check the range is suitable).
A
For your information
Running the activity
The activity sheet suggests a group practical. The teacher may prefer to
demonstrate the circuit, in which case there will be sufficient meters to place
them in each position in the circuit, instead of moving them.
The sheet provides a results table for pupils to copy, and instructions to build the
circuit and record the ammeter reading at three positions in the circuit.
Expected outcomes
The electric current is the same at every point in the circuit.
Pitfalls
If you are using standard dry cells, then beware those that are ‘flat’. Note that
they cannot be checked with a voltmeter, only across a lamp. Also wires
sometimes fracture inside the insulation. It is wise to have a tray for faulty
components, so that they do not go back into stock. It is good practice to
encourage pupils to disconnect cells when they are not using the circuits, to help
them last longer.
If analogue meters are used, they must be checked beforehand to ensure that they
will read the same current. Pupils may be concerned when ammeters give
negative readings. Remind them to swap the wires.
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All the way round
J2a
M
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^ _
UG LP
Activity
Core
You are going to measure the electric current in different
positions around a simple circuit.
Obtaining evidence
1
Make a table like the one below to record your results.
Position of ammeter
TN TC
Ammeter reading in amps
between positive () end
of battery and lamp
between the lamps
between negative () end
of battery and lamp
2
Connect the circuit as shown in the diagram. Switch on.
ⴙ
ⴚ
ⴙ
ⴚ
A
ⴙ
3
4
5
6
7
ⴚ
Record the ammeter reading in your table. If the ammeter
gives a negative reading, just swap over the two wires
connecting it.
Disconnect the ammeter and reconnect it between the two
lamps.
Switch on and record the ammeter reading in your table.
Disconnect the ammeter and reconnect it on the other side of
the circuit, between the switch and the lamp.
Switch on and record the reading in your table.
Remember
to switch off the
circuit before you
make any
changes.
Considering the evidence
1 What can you say about the electric current around the circuit?
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Brighter and dimmer
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UG LP
Teacher
activity notes
Type
Purpose
Differentiation
Practical
Pupils investigate changing number of cells and the number of lamps in a circuit.
Core, Help
Running the activity
Pupils work in groups of two or three. It may be more successful to give each
group three wires initially, then give them additional wires as they add further
components, to save confusion.
Core: Pupils make a prediction about changing the number of cells and the
TC number of lamps. They build the circuits without the aid of a diagram, and write
sentences to describe their findings.
Help: Pupils are provided with a diagram of the circuit. Structured questions lead
them to make their predictions and describe their results on the sheet.
Expected outcomes
Pupils see that more cells supply more energy, so the light is brighter. If there are
more lamps in the circuit, then the energy must be shared between them, so the
light is dimmer.
Pitfalls
If you are using standard dry cells, then beware those that are ‘flat’. Note that
they cannot be checked with a voltmeter, only across a lamp. Also wires
sometimes fracture inside the insulation. It is wise to have a tray for faulty
components, so that they do not go back into stock. It is good practice to
encourage pupils to disconnect cells when they are not using the circuits, to help
them last longer.
With 1.5 V cells and 2.5 V lamps the lamps are unlikely to blow, but beware of
pupils collecting more cells from other groups!
Answers
Core:
1 the number of cells or the number of lamps
2 The lamp would be brighter because more cells supply more energy.
3 The lamps would be dimmer because they have to share the energy.
4 as for Q2 and Q3 above
5 Check pupils’ predictions.
Help:
1 cell (or battery), lamp, switch
Missing/correct words are as follows:
2 energy, brighter, dimmer, the energy must be shared between more lamps.
3 brighter, dimmer
4 Check pupils’ predictions.
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Brighter and dimmer
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UG LP
TN
Technician
activity notes
Type
Purpose
Differentiation
Practical
Pupils investigate changing number of cells and the number of lamps in a circuit.
Core, Help
Equipment
For each group:
● two 1.5 V cells in holder
● three 2.5 V lamps in holders
● five connecting wires.
For your information
Running the activity
Pupils work in groups of two or three. It may be more successful to give each
group three wires initially, then give them additional wires as they add further
components, to save confusion.
Core: Pupils make a prediction about changing the number of cells and the
number of lamps. They build the circuits without the aid of a diagram, and write
sentences to describe their findings.
Help: Pupils are provided with a diagram of the circuit. Structured questions lead
them to make their predictions and describe their results on the sheet.
Expected outcomes
Pupils see that more cells supply more energy, so the light is brighter. If there are
more lamps in the circuit, then the energy must be shared between them, so the
light is dimmer.
Pitfalls
If you are using standard dry cells, then beware those that are ‘flat’. Note that
they cannot be checked with a voltmeter, only across a lamp. Also wires
sometimes fracture inside the insulation. It is wise to have a tray for faulty
components, so that they do not go back into stock. It is good practice to
encourage pupils to disconnect cells when they are not using the circuits, to help
them last longer.
With 1.5 V cells and 2.5 V lamps the lamps are unlikely to blow, but beware of
pupils collecting more cells from other groups!
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Brighter and dimmer
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UG LP
6
Activity
Core
You are going to find out how to change the brightness of a
lamp.
Predicting
1 A simple circuit has:
● one cell
● one lamp
● connected in a simple loop with a switch.
TN TC
If you keep the simple loop and switch, what in this list can you
change?
2 What do you expect to happen if you use more than one cell?
Give a reason for your answer.
3 What do you expect to happen if you use more than one lamp?
Give a reason for your answer.
Obtaining evidence
1
2
3
4
Connect one cell to one lamp. Switch on and record how
bright it is.
Connect a battery of two cells to one lamp. Switch on and
record how bright it is now.
Connect a battery of two cells to two lamps. Are the lamps
brighter or dimmer than in step 2?
Now try a battery of two cells with three lamps.
Remember
to switch off the
circuit before you
make any
changes.
Presenting the results
5
Write down two sentences to describe what you have found out.
Considering the evidence
4 Use ideas about energy to try to explain what you have seen.
5 Was your prediction correct?
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Brighter and dimmer
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Activity
Help
You are going to find out how to change the brightness of a lamp.
Predicting
This simple circuit has just one cell connected in a loop to one lamp, with a switch.
^ _
ⴙ
ⴚ
UG LP
TN TC
1 Name the three components in the picture of the circuit.
.............................................................................................................................................................................................
2 Complete these sentences by underlining the correct words and filling the gaps.
Cells are a store of ...................................... .
I expect that if I add an extra cell to my circuit, then the lamp will be
brighter/dimmer.
I expect that if I add an extra lamp to my circuit, then the light will be
dimmer/brighter. This is because
.........................................................................................................
.............................................................................................................................................................................................
Obtaining evidence
1
2
3
4
Connect one cell to one lamp. Switch on. Write down how
bright (or dim) it is.
Connect two cells to one lamp. Look at how bright it is.
Connect two cells to two lamps. Are the lamps brighter or
dimmer than in step 2?
Now try two cells and three lamps.
Remember
to switch off the
circuit before you
make any
changes.
Presenting the results
3 Complete these sentences.
More cells in the circuit make the lamp
..............................................................................................
More lamps in the circuit make the lamps ........................................................................................
4 Was your prediction correct?
..........................
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Investigating electric current
J2c
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Teacher
activity notes
Type
Purpose
Differentiation
Practical
Pupils measure current as they change the number of cells and lamps in a circuit.
Core (Help), Extension
Running the activity
Pupils work in groups to build circuits and measure the current as they change the
numbers of cells or lamps.
UG LP Core (Help): Pupils copy the results table provided, and follow the instructions to
build the circuits and measure the current. For Help, there are optional prompts at
TC the foot of the Core sheet to help pupils consider their results, which can be cut
off if not required.
Extension: Pupils build their circuits from a circuit diagram. As for Core, they copy
the results table provided, and follow the instructions to build the circuits and
measure the current. They also consider the effect of a dimmer switch.
Other relevant material
Skill sheet 17: Reading an ammeter
Expected outcomes
The current is higher with two cells than with one. (It is unlikely to be exactly
double, because of the cell’s internal resistance, and the variation of the filament
resistance with temperature.)
The current is lower with two lamps than with one.
Extension: Varying the slide position or turning the knob on the variable
resistance changes the current and the brightness of the lamp.
Pitfalls
If you are using standard dry cells, then beware those that are ‘flat’. Note that they
cannot be checked with a voltmeter, only across a lamp. Also wires sometimes
fracture inside the insulation. It is wise to have a tray for faulty components, so
that they do not go back into stock. It is good practice to encourage pupils to
disconnect cells when they are not using the circuits, to help them last longer.
Check that pupils are reading ammeters correctly. Analogue ammeters may be
better for this activity. If digital ones are used they should be switched to the
correct range in advance. (Note that some cheaper digital meters have their fuses
blown if the large current range is switched during use.)
Pupils may be concerned when ammeters give negative readings. Remind them to
swap the wires.
Answers
Core (Help):
1 Check pupils’ predictions.
2 a If there are more cells in the circuit then the current is higher/bigger.
b If there are more lamps in the circuit then the current is lower/smaller.
Extension:
1 Check pupils’ predictions.
2 If there are more cells in the circuit then the current is higher/bigger.
If there are more lamps in the circuit then the current is lower/smaller.
3 The higher the current, the brighter the lamp or more results are needed to be
able to generalise.
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Investigating electric current
J2c
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Technician
activity notes
Type
Purpose
Differentiation
Practical
Pupils measure current as they change the number of cells and lamps in a circuit.
Core (Help), Extension
Other relevant material
Skill sheet 17: Reading an ammeter
UG LP Equipment
TN
For each group:
●
●
●
●
●
●
two 1.5 V cells in holder
two 2.5 V lamps in holders
a DC ammeter (check that the range is suitable)
a switch
five connecting wires
variable resistor (for Extension).
A
For your information
Running the activity
Pupils work in groups to build circuits and measure the current as they change the
numbers of cells or lamps.
Core (Help): Pupils copy the results table provided, and follow the instructions to
build the circuits and measure the current. For Help, there are optional prompts at
the foot of the Core sheet to help pupils consider their results, which can be cut
off if not required.
Extension: Pupils build their circuits from a circuit diagram. As for Core, they copy
the results table provided, and follow the instructions to build the circuits and
measure the current. They also consider the effect of a dimmer switch.
Expected outcomes
The current is higher with two cells than with one. (It is unlikely to be exactly
double, because of the cell’s internal resistance, and the variation of the filament
resistance with temperature.)
The current is lower with two lamps than with one.
Extension: Varying the slide position or turning the knob on the variable
resistance changes the current and the brightness of the lamp.
Pitfalls
If you are using standard dry cells, then beware those that are ‘flat’. Note that
they cannot be checked with a voltmeter, only across a lamp. Also wires
sometimes fracture inside the insulation. It is wise to have a tray for faulty
components, so that they do not go back into stock. It is good practice to
encourage pupils to disconnect cells when they are not using the circuits, to help
them last longer.
Check that pupils are reading ammeters correctly. Analogue ammeters may be
better for this activity. If digital ones are used they should be switched to the
correct range in advance. (Note that some cheaper digital meters have their fuses
blown if the large current range is switched during use.)
Pupils may be concerned when ammeters give negative readings. Remind them to
swap the wires.
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Investigating electric current
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Activity
Core
You are going to use an ammeter to find out how the current
changes when you change the number of cells or lamps in the
circuit.
^ _ Obtaining evidence
UG LP 1
TN TC
Make a table like this to record your results.
Components in circuit
ⴙ
ⴚ
Current in amps
1 cell, 1 lamp
2 cells, 1 lamp
ⴙ
ⴚ
2 cells, 2 lamps
1 cell, 2 lamps:
prediction
1 cell, 2 lamps:
actual result
2
3
4
5
6
A
Make the circuit shown in the diagram. Your ammeter may
Don’t leave
the
circuit
switched
look different from the one shown.
on for long. When you
Switch on and measure the current. Ask your teacher
are not recording the
to check that your reading is correct. Record it in the
current, switch
off.
first row of your table.
Add another cell to your circuit. Measure and record the current.
Add another lamp to the circuit in 4. Measure the current again.
Predict what the current would be if you had one cell and two
lamps. Write your prediction in your table, then build the circuit
and check.
Considering the evidence
1 Was your prediction correct?
2 Write two sentences to describe what you have found out about
how the current changes when you change the number of cells and lamps.
Help
Complete these sentences to answer question 2 :
a If there are more cells in the circuit then the current is ...................................................................
b If there are more lamps in the circuit then the current is
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.............................................................
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Investigating electric current
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Activity
Extension
You are going to use an ammeter to find out how the current
changes when you change the number of cells or lamps in the
circuit. You will also find out how a dimmer switch works.
^ _ Obtaining evidence
UG LP 1
TN TC
Make a table like the one below to record your results.
Components in circuit
Current in amps
1 cell, 1 lamp
A
2
3
4
5
6
7
Make the circuit shown in the diagram opposite.
Switch on and measure the current. Ask your teacher
Don’t leave
to check that your reading is correct. Record it in the
the circuit switched
on for long. When you
first row of your table.
are not recording the
If the lamp doesn’t light and the ammeter reading is zero,
current, switch
then you have not got a complete circuit.
off.
● Check all the connections.
● Try the circuit with the ammeter removed.
● Try a different lamp.
● Finally try different cells.
● If you still cannot get your circuit to work, ask your teacher
for help.
Add another cell to your circuit. Measure and record the current.
Add another lamp to the circuit in 4. Measure the current again.
Predict what the current would be if you had one cell and two
lamps. Write your prediction in your table, then build the circuit
and record the result.
Dimmer switches use variable resistors.
8
Connect two cells, one lamp and a variable resistor in a circuit.
Find out and record what happens to the current and the
brightness of the lamp as you adjust the variable resistor.
Considering the evidence
1 Was your prediction in 7 correct?
2 Write two sentences to describe what you have found out about
how the current changes when you change the number of cells
and lamps.
3 Do you have enough evidence to make up any general rules
about the current in a circuit and the brightness of a lamp?
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Parallel circuits
J3a
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Teacher
activity notes
Type
Purpose
Differentiation
Practical
Pupils find the current at different points in a parallel circuit.
Core, Help
Running the activity
You may want to remind pupils that the current is the same all around a series circuit.
Pupils work in groups to build a parallel circuit and measure the current at three
UG LP positions around it. You may need to show them how to ‘stack’ 4 mm plugs or other
TC
connectors to create parallel connections.
If necessary, point out that it is good practice to lay components out as they appear
in the circuit diagram, and then add the connections. Pupils may need reassurance
that topologically equivalent circuits are valid, even thought the junctions are not in
exactly the same position as in the diagrams.
Core: Pupils use the circuit diagrams in the table to build their circuits. They make a
copy of the table including circuit diagrams to record their results.
Help: Pupils build their circuits from pictures of the circuits. They record their results
in the table on the sheet, and structured questions lead them to consider their
evidence.
Other relevant material
Skill sheet 17: Reading an ammeter
Expected outcomes
The current varies at different points in a parallel circuit, dividing at the branches.
The sum of the currents in the branches is equal to the total current.
Pitfalls
If you are using standard dry cells, then beware those that are ‘flat’. Note that they
cannot be checked with a voltmeter, only across a lamp. Also wires sometimes
fracture inside the insulation. It is wise to have a tray for faulty components, so that
they do not go back into stock. It is good practice to encourage pupils to disconnect
cells when they are not using the circuits, to help them last longer.
Check that pupils are reading ammeters correctly. Analogue ammeters may be better
for this activity. If digital ones are used they should be switched to the correct range
in advance. (Note that some cheaper digital meters have their fuses blown if the
large current range is switched during use.)
Pupils may be concerned when ammeters give negative readings. Remind them to
swap the wires.
Answers
Core:
1 No, the current is not the same in all three positions. Pupils should quote their
results to support this.
2 If you add the currents measured at positions 2 and 3, the total equals the
current at position 1.
Help:
1 Check pupils’ additions.
2 no
3 Missing words are as follows:
bigger than, equal to, smaller than, equal to
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Parallel circuits
J3a
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Technician
activity notes
Type
Purpose
Differentiation
Practical
Pupils find the current at different points in a parallel circuit.
Core, Help
Other relevant material
Skill sheet 17: Reading an ammeter
UG LP Equipment
TN
For each group:
●
●
●
●
●
two 1.5 V cells in holder
two 2.5 V lamps in holders
a DC ammeter, range 0–1 A
six connecting wires
a switch.
A
A
A
For your information
Running the activity
You may want to remind pupils that the current is the same all around a series
circuit.
Pupils work in groups to build a parallel circuit and measure the current at three
positions around it. You may need to show them how to ‘stack’ 4 mm plugs or
other connectors to create parallel connections.
If necessary, point out that it is good practice to lay components out as they
appear in the circuit diagram, and then add the connections. Pupils may need
reassurance that topologically equivalent circuits are valid, even thought the
junctions are not in exactly the same position as in the diagrams.
Core: Pupils use the circuit diagrams in the table to build their circuits. They make
a copy of the table including circuit diagrams to record their results.
Help: Pupils build their circuits from pictures of the circuits. They record their
results in the table on the sheet, and structured questions lead them to consider
their evidence.
Expected outcomes
The current varies at different points in a parallel circuit, dividing at the branches.
The sum of the currents in the branches is equal to the total current.
Pitfalls
If you are using standard dry cells, then beware those that are ‘flat’. Note that
they cannot be checked with a voltmeter, only across a lamp. Also wires
sometimes fracture inside the insulation. It is wise to have a tray for faulty
components, so that they do not go back into stock. It is good practice to
encourage pupils to disconnect cells when they are not using the circuits, to help
them last longer.
Check that pupils are reading ammeters correctly. Analogue ammeters may be
better for this activity. If digital ones are used they should be switched to the
correct range in advance. (Note that some cheaper digital meters have their fuses
blown if the large current range is switched during use.)
Pupils may be concerned when ammeters give negative readings. Remind them to
swap the wires.
© Harcourt Education Ltd 2003 Catalyst 1
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Parallel circuits
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Activity
Core
You are going to build a parallel circuit and investigate how the electric
current splits up in a parallel circuit.
Equipment
● two cells
● wires
● a switch
^ _ ● two lamps
UG LP ● an ammeter
TN TC
Obtaining evidence
1
Make a table like the one below to record your results.
Circuit
Components in circuit
Current in amps
parallel,
position 1
A
parallel,
position 2
A
parallel,
position 3
A
2
3
4
Build a simple parallel circuit like the top one in the table.
Measure the current with the ammeter in the circuit at position 1.
● If both lamps light, record the current.
● If one or both lamps don’t light, find the problem!
Put the ammeter at positions 2 and 3 and measure the current each time.
Considering the evidence
1 Is the current the same at all points in the parallel circuit?
2 Can you see a relationship between the currents at positions 1, 2, and 3 in
the parallel circuit?
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Activity
Help
Parallel circuits
You are going to build a parallel circuit and investigate how the
electric current splits up in a parallel circuit.
Equipment
● two cells
UG LP ● two lamps
TN TC ● an ammeter
● wires
● a switch
Obtaining evidence
1
2
3
4
Build a simple parallel circuit with
two lamps, two cells and a switch.
Put the ammeter at position 1 as
shown here.
If both lamps light, record the
current in the table on Sheet 2.
If one or both lamps don’t light,
find the problem!
Don’t leave
the circuit switched
on for long. When you
are not recording the
current, switch
off.
Switch off and move the ammeter to
position 2, like this. Remember to
rejoin the circuit where you remove
the ammeter.
Switch on and record the current
in the table.
Position 1
ⴙ
ⴙ
ⴚ
ⴙ
ⴚ
ⴚ
ammeter
Position 2
ⴙ
ⴚ
ⴙ
ⴚ
ⴙ
ⴚ
ammeter
Position 3
5
Repeat steps 3 and 4 for position 3.
ⴙ
ⴚ
ⴙ
ⴚ
ⴙ
ⴚ
ammeter
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J3a
Parallel circuits (continued)
M
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Presenting the results
p
?
Record your results in this table.
t
u
^ _
UG LP
Activity
Help
Circuit
Components in circuit
Current in amps
parallel,
position 1
TN TC
A
parallel,
position 2
A
parallel,
position 3
A
Considering the evidence
1 How much current is going through both lamps?
Work it out by adding the readings at positions 2 and 3. ...................................................................
2 Is the current the same at all points in the parallel circuit?
................................................................
3 Complete these sentences using the words below.
bigger than
smaller than
equal to
The current at position 1 is .................................................. the current at position 2.
The current at position 2 is .................................................. the current at position 3.
The current at position 3 is .................................................. the current at position 1.
The total current at positions 2 and 3 is .................................................. the current at position 1.
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Lighting circuits
J3b
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UG LP
Type
Purpose
Practical
Pupils build a parallel circuit with a master switch to see how the lamps can be
switched independently or all together.
Teacher
activity notes
Differentiation
Core, Help
Running the activity
Pupils work in groups of two or three. You may need to show them how to ‘stack’
4 mm plugs or other connectors to create parallel connections.
Core: Pupils design and build a parallel lighting circuit.
TC Help: Pupils consider the action of a pictured parallel circuit, then build it to see if
they are correct. If necessary, point out that it is good practice to lay components
out as they appear in the circuit diagram, and then add the connections. Pupils
may need reassurance that topologically equivalent circuits are valid, even
thought the junctions are not in exactly the same position as in the diagrams.
Expected outcomes
Pupils should see that a parallel circuit can have current flowing through one
branch at a time. A master switch turns off the current to all branches.
Pitfalls
If you are using standard dry cells, then beware those that are ‘flat’. Note that
they cannot be checked with a voltmeter, only across a lamp. Also wires
sometimes fracture inside the insulation. It is wise to have a tray for faulty
components, so that they do not go back into stock. It is good practice to
encourage pupils to disconnect cells when they are not using the circuits, to help
them last longer.
If the pupils use 1.5 V cells and 2.5 V lamps then the lamps are unlikely to blow,
but beware of pupils collecting more cells from other groups!
Answers
Core:
1 The master switch is the one in the single wire to the battery. This switches
off the current to all the branches. Switches in each branch control that
branch only.
Help: Missing words are as follows:
1 both lamps, one lamp, master
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Lighting circuits
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Technician
activity notes
Type
Purpose
Differentiation
Practical
Pupils build a parallel circuit with a master switch to see how the lamps can be
switched independently or all together.
Core, Help
Equipment
For each group:
UG LP ● two 1.5 V cells in holder
TN
● two 2.5 V lamps in holders
● three switches
● seven connecting wires.
For your information
Running the activity
Pupils work in groups of two or three. You may need to show them how to ‘stack’
4 mm plugs or other connectors to create parallel connections.
Core: Pupils design and build a parallel lighting circuit.
Help: Pupils consider the action of a pictured parallel circuit, then build it to see if
they are correct. If necessary, point out that it is good practice to lay components
out as they appear in the circuit diagram, and then add the connections. Pupils
may need reassurance that topologically equivalent circuits are valid, even
thought the junctions are not in exactly the same position as in the diagrams.
Expected outcomes
Pupils should see that a parallel circuit can have current flowing through one
branch at a time. A master switch turns off the current to all branches.
Pitfalls
If you are using standard dry cells, then beware those that are ‘flat’. Note that
they cannot be checked with a voltmeter, only across a lamp. Also wires
sometimes fracture inside the insulation. It is wise to have a tray for faulty
components, so that they do not go back into stock. It is good practice to
encourage pupils to disconnect cells when they are not using the circuits, to help
them last longer.
If the pupils use 1.5 V cells and 2.5 V lamps then the lamps are unlikely to blow,
but beware of pupils collecting more cells from other groups!
© Harcourt Education Ltd 2003 Catalyst 1
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Lighting circuits
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6
Activity
Core
You are going to design a circuit with two lamps, so that both
light brightly. Each lamp will have its own switch, and there will
be a master switch, that can switch both lamps off.
^ _ Equipment
UG LP ●
TN TC ●
●
●
two cells
two lamps
three switches
wires
Planning
1
2
3
4
Draw a circuit that you think will work. Use a battery of two cells.
Draw a coloured line around your circuit to show the path of the
electricity when just one lamp lights.
Draw a line in a different colour to show the path when just the
other lamp lights.
Label the master switch.
Obtaining evidence
5
6
Build your circuit.
Test that each switch does what you need it to do. If it does not,
look back at your circuit diagram and change it if necessary.
Considering the evidence
1 Explain why your circuit worked.
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Lighting circuits
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Activity
Help
You are going to build a circuit with two lamps, that both light
brightly. Each lamp will have its own switch, and there will be a
master switch, that can switch both lamps off.
Planning
ⴙ
UG LP
ⴚ
ⴙ
ⴚ
TN TC
switch 1
switch 2
switch 3
1
2
3
Draw a coloured line round the circuit to show the path of the electricity when
just switch 1 and switch 2 are closed. Colour the lamp that will light.
Draw a line in a different colour to show the path when just the other lamp lights.
The master switch can switch both lamps off. Label it on the diagram.
Obtaining evidence
4
5
Build the circuit shown in the diagram.
Test that each switch does what it should do. If not, look back at the picture and
change your circuit if you need to.
Considering the evidence
1 Complete these sentences using the words below.
master
both lamps
one lamp
Switch 1 controls ........................................... Switches 2 and 3 each control .......................................... .
Switch 1 is the .......................... switch in this parallel circuit.
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Developing the light bulb
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Type
Purpose
Paper
More able pupils extend their understanding of the historical development of the
light lamp.
Teacher
activity notes
Differentiation
Extension
Running the activity
Pupils work individually or in pairs to read the biographies of the scientists and
answer the questions on the sheet. They gain an insight into how scientific
discoveries can stem from the work of several scientists working at different times,
and appreciate the commercial value of inventions.
ICT opportunities
Biographies of Humphrey Davy in the CD-ROM Eyewitness Encyclopedia of Science
2.0 (Dorling Kindersley), The Way Things Work (Dorling Kindersley) and Encarta
(Microsoft®).
Biographies of Edison in the CD-ROM The Way Things Work and Encarta.
Biography of Swan in the CD-ROM The Way Things Work.
Answers
1 Carbon, because you can heat it to a higher temperature before it melts.
2 Platinum is much more expensive than carbon.
3 a carbon dioxide
b platinum oxide
4 If the number of light bulbs in the pupil’s home is n, the sum is
£(n 5 000 000 2)/(4 240). If n is 10, the patent was worth about £104 000
per year in Britain.
5 individual answers
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Developing the light bulb
Activity
Extension
You are going to study the biographies of three of the scientists involved in
developing the electric filament lamp.
^ _
UG LP
TN
Humphrey Davy was born in Cornwall
in 1778. He was a very famous
scientist during his lifetime. In 1801,
he tried to make an electric filament
lamp with strips of platinum, but the
platinum strips burned.
Joseph Swan was born in Sunderland,
England in 1828. He started working
on electric filament lamps in 1848, but
the filaments burned away in the air.
He invented the carbon filament lamp
in 1878, soon after the vacuum pump
was invented. The pump was needed
to take the air out of the bulbs.
Thomas Edison was born in America
in 1847. Edison was a great inventor,
who held a world record of 1093
patents. Edison invented a carbon
filament bulb in 1879. He worked
independently of Swan, but based his
idea on some of Swan’s early work.
Many materials glow when they are heated. When a material is used as a filament in a lamp,
it needs to glow but not melt. Carbon melts at 3652 °C and platinum melts at 1772 °C.
1 Based on the information above about melting points, which material is more suitable
for the filament of an electric lamp? Explain your answer.
2 Based on your general knowledge about carbon and platinum, what other reason is
there for using carbon rather than platinum?
Before the invention of the vacuum pump, there was a problem with the filament
burning away in the air.
3 What substance would be made when:
a carbon
b platinum burned?
Inventors patent their inventions. This means the inventor must be paid a fee by people
using the invention.
4 Imagine that the inventor of
● How many light bulbs are there in your home?
● There were approximately 5 million households
in Britain in the late nineteenth century.
● An early electric filament lamp lasted 6 months.
● There were 240 old pennies in a pound.
● A farthing was one quarter of an old penny.
the filament lamp received one
farthing for every light bulb sold.
Try to estimate how much the
patent was worth per year in
Britain, using the information
opposite. Show how you came to
this amount of money.
5 Most people think that Thomas Edison invented the electric filament lamp. Imagine you
are a friend of Joseph Swan. You visit America in 1885 and you are very surprised that no
one has heard of Joseph Swan, and that everyone thinks that electric filament lamps were
invented by Thomas Edison. Write a newspaper article telling the American public about
Joseph Swan and his contribution towards the development of the electric filament lamp.
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‘Class and matches’ model
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Teacher
activity notes
Type
Purpose
Differentiation
Practical (demonstration)
Pupils experience using models.
(no pupil sheets)
Running the activity
A ‘circuit’ is marked on the floor with chalk or tape. The circle must be big
enough for all members of the class to walk around at once (the pupils should be
quite close together).
One teacher, or a trusted pupil, stands at one point on the circle. He or she is the
battery and will put energy into the circuit by giving out matches. Another
teacher stands opposite, again on the ‘circuit’. He or she is the lamp, and will take
energy out of the circuit by taking in the matches and striking them.
The pupils stand on the circle. They walk slowly around the circle and collect a
match from the ‘battery’ as they go by, and deliver the match to the ‘lamp’. The
pupils themselves actually represent the charge carriers, but as charge carriers
have not been introduced, the moving pupils are considered to represent the
current. Pupils can be asked to speed up a little to represent an increase in current,
or slow down to represent a decrease in current.
Other relevant material
For the class:
● chalk or tape to mark a circle on the ground
● a large box of very long household safety matches.
Pitfalls
Use the largest type of household matches, so they are easily seen.
Safety notes
If only one teacher is available, he or she should be the ‘lamp’ (who strikes the
matches).
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Christmas tree lights
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Teacher
activity notes
Type
Purpose
Differentiation
Paper
Pupils draw circuits to extend their understanding of the difference between series
and parallel circuits.
Core
Running the activity
Pupils work individually or in pairs to read the pupil sheet and answer the
questions.
Answers
1 1 series, 2 parallel
2 In parallel, because when you turn one light off, the rest stay on.
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Christmas tree lights
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Activity
Core
Old-fashioned tree lights used to all go out if one bulb ‘blew’.
This was very annoying because you could not tell immediately
which bulb had gone wrong. You had to spend ages replacing
each one in turn.
^ _ 1 Draw a circuit with six lights in it that would behave this way.
UG LP 2
TN
Now redraw your circuit so that if one bulb blew only that one
would go out.
1 What name do we give to each of your circuits?
2 In which of these two ways do you think the lights in your house
are connected? Give a reason for your answer.
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Christmas tree lights
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Activity
Core
Old-fashioned tree lights used to all go out if one bulb ‘blew’.
This was very annoying because you could not tell immediately
which bulb had gone wrong. You had to spend ages replacing
each one in turn.
1
2
Draw a circuit with six lights in it that would behave this way.
Now redraw your circuit so that if one bulb blew only that one
would go out.
1 What name do we give to each of your circuits?
2 In which of these two ways do you think the lights in your house
are connected? Give a reason for your answer.
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The weakest link
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UG LP
Teacher
activity notes
Type
Purpose
Differentiation
Practical
Pupils use wire wool as a fuse and test various pieces of fuse wire to the current flowing
through the wire, which will cause it to melt.
Core, Help
Running the activity
Pupils work in groups to build a circuit into which they put a copper wire and then
strands of wire wool to model the effect of a fuse in a circuit. They then use a circuit
with a power supply and ammeter to find out at what current fuse wire will melt.
TC Try out the experiment yourself with the equipment you have available in school. If
you think the group will not be able to melt the wire wool sensibly and safely,
demonstrate this first part of the experiment. Limit the wire wool available to a few
strands for each group.
Experiment in advance with the length of fuse wire and the rating to try and keep
the current and voltage as low as possible.
Make sure that the pupils set the power supply to the lowest DC voltage, and that they
leave the current flowing for perhaps 30 s as the fuse wire will not blow immediately.
Core: Pupils build the circuits shown on the sheet, and plan how they will test fuse
wire.
Help: Full instructions are given to build the circuits, and structured questions lead
pupils to consider their evidence.
Other relevant material
Skill sheet 17: Reading an ammeter
Expected outcomes
The copper wire does not burn through but conducts safely.
The wire wool burns through, and this breaks the circuit so the lamp goes out. The
same happens with fuse wire, depending on the current.
Pitfalls
If you are using standard dry cells, then beware those that are ‘flat’. Note that they
cannot be checked with a voltmeter, only across a lamp. Also wires sometimes
fracture inside the insulation. It is wise to have a tray for faulty components, so that
they do not go back into stock. It is good practice to encourage pupils to disconnect
cells when they are not using the circuits, to help them last longer.
Check that pupils are reading ammeters correctly. Analogue ammeters may be better
for this activity. If digital ones are used they should be switched to the correct range
in advance. (Note that some cheaper digital meters have their fuses blown if the
large current range is switched during use.)
Pupils may be concerned when ammeters give negative readings. Remind them to
swap the wires.
The wire wool activity is popular, but it runs down the cells quickly, so do not allow
pupils to carry it on for too long.
Safety notes
Eye protection should be worn. The wire wool sparks. Warn pupils that wire wool
has sharp strands. They often penetrate the skin to leave behind minute metal
‘splinters’.
If pupils have not used low voltage power supplies before you will need to explain
how they should use them safely.
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The weakest link (continued)
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Teacher
activity notes
Answers
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Core:
1 The strands of wire wool melted and broke the circuit.
2 It can stop a fire starting or electrical equipment being damaged by too high a
current.
3 Check pupils’ results – the fuse wire would be useful for currents just under
the current at which it melted.
UG LP Help:
TC
1 The wire wool melted and broke the circuit, so the lamp went out.
2 The wire wool is much thinner or can’t carry as big a current.
3 the wire wool
4 , 5 Check pupils’ results – the fuse wire would be useful for currents just under
the current at which it melted.
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The weakest link
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TN
Technician
activity notes
Type
Purpose
Differentiation
Practical
Pupils use wire wool as a fuse and test various pieces of fuse wire to the current flowing
through the wire which will cause it to melt.
Core, Help
Other relevant material
Skill sheet 17: Reading an ammeter
Equipment
For each group:
First test:
● three cells
● a lamp
● copper wire
● a few strands of wire wool about 1 cm long
● a switch
● four connecting wires (two with crocodile clip ends)
● a heatproof mat.
Second test:
● a low voltage power supply
● a DC ammeter
● three connecting wires (two with crocodile clip ends)
● a variety of low rated fuse wire or fuses (2 A and lower if possible)
● a heatproof mat.
For your information
Running the activity
Pupils work in groups to build a circuit into which they put a copper wire and
then strands of wire wool to model the effect of a fuse in a circuit. They then use
a circuit with a power supply and ammeter to find out at what current fuse wire
will melt.
Try out the experiment yourself with the equipment you have available in school.
If you think the group will not be able to melt the wire wool sensibly and safely,
demonstrate this first part of the experiment. Limit the wire wool available to a
few strands for each group.
Experiment in advance with the length of fuse wire and the rating to try and keep
the current and voltage as low as possible.
Make sure that the pupils set the power supply to the lowest DC voltage, and that
they leave the current flowing for perhaps 30 s as the fuse wire will not blow
immediately.
Core: Pupils build the circuits shown on the sheet, and plan how they will test
fuse wire.
Help: Full instructions are given to build the circuits, and structured questions
lead pupils to consider their evidence.
Expected outcomes
The copper wire does not burn through but conducts safely.
The wire wool burns through, and this breaks the circuit so the lamp goes out.
The same happens with fuse wire, depending on the current.
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The weakest link (continued)
Technician
activity notes
Pitfalls
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If you are using standard dry cells, then beware those that are ‘flat’. Note that
they cannot be checked with a voltmeter, only across a lamp. Also wires
sometimes fracture inside the insulation. It is wise to have a tray for faulty
components, so that they do not go back into stock. It is good practice to
encourage pupils to disconnect cells when they are not using the circuits, to help
them last longer.
Check that pupils are reading ammeters correctly. Analogue ammeters may be
UG LP better for this activity. If digital ones are used they should be switched to the
TN
correct range in advance. (Note that some cheaper digital meters have their fuses
blown if the large current range is switched during use.)
Pupils may be concerned when ammeters give negative readings. Remind them to
swap the wires.
The wire wool activity is popular, but it runs down the cells quickly, so do not
allow pupils to carry it on for too long.
Safety notes
Eye protection should be worn. The wire wool sparks. Warn pupils that wire wool
has sharp strands. They often penetrate the skin to leave behind minute metal
‘splinters’.
If pupils have not used low voltage power supplies before you will need to explain
how they should use them safely.
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Activity
Core
The weakest link
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In this activity you are going to investigate how a fuse protects a
circuit.
Wear eye
protection.
Wire wool has
sharp strands
– take care not to
cut yourself. When
you switch on the
circuit, make sure
you are not touching
the wire wool.
!
Equipment
● First test: three cells, a lamp, copper wire, wire wool, a switch,
UG LP
connecting wires (two with crocodile clip ends), a heatproof mat
TN TC ● Second test: a low voltage power supply, an ammeter, connecting
wires (two with crocodile clip ends), a variety of fuse wires or fuses
(2 A and lower if possible), a heatproof mat
Obtaining evidence: First test
1
2
3
4
ⴙ
ⴚ
ⴙ
Connect up this circuit, using copper
wire between the crocodile clips.
Switch on and check that the lamp lights.
Switch off. Replace the piece of wire with
a few strands of wire wool about 1 cm long.
Switch on and record what happens.
ⴚ
ⴙ
ⴚ
heatproof
mat
Considering the evidence
1 Is this what you expected to happen?
Can you explain why it happened?
(If you did not get the result you expected,
can you explain why not?)
2 How can this behaviour be useful in a circuit?
Obtaining evidence: Second test
5
6
Plan how you would test some wire to see
whether it is suitable to be used as fuse wire.
Decide how to record your results.
Check your plan with your teacher, then carry
it out.
Considering the evidence
3 Could the wire you tested be used as fuse wire?
power supply
ⴙⴚ
ⴙ ⴚ
heatproof mat
For what current, or range of currents, would
it be useful?
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The weakest link
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Activity
Help
In this activity you are going to investigate how a fuse protects a
circuit.
Wear eye
protection.
Wire wool has
sharp strands
– take care not to
cut yourself. When
you switch on the
circuit, make sure
you are not touching
the wire wool.
!
Equipment
^ _ ● First test: three cells, a lamp, copper wire, wire wool, a switch,
connecting wires (two with crocodile clip ends), a heatproof mat
UG LP ● Second test: a low voltage power supply, an ammeter, connecting
wires (two with crocodile clip ends), a variety of fuse wires or fuses
TN TC
(2 A and lower if possible), a heatproof mat
ⴙ
Obtaining evidence: First test
1
2
3
ⴚ
ⴙ
ⴚ
ⴙ
ⴚ
Set up this circuit, using copper wire between
the crocodile clips:
Switch on and check that the lamp lights.
Switch off and replace the piece of wire with a
few strands of wire wool about 1 cm long.
heatproof
mat
Considering the evidence
1 What happened when the current flowed through the thin wire wool?
...................................................................................................................................
2 What is the big difference between the copper wire and the wire wool?
...................................................................................................................................
3 Complete this sentence:
The weakest link in the circuit was .............................................................................
power supply
Obtaining evidence: Second test
4
5
6
7
8
9
Connect up the circuit shown in the diagram.
Put a wire between the crocodile clips.
Switch on for 30 seconds or until the wire melts.
If the wire melts, record the current in the table.
If the wire doesn’t melt, increase the current and
try again.
Repeat steps 5 to 8 with the other wires.
Considering the evidence
ⴙⴚ
ⴙ ⴚ
heatproof mat
Wire being tested Current in amps when wire melted
4 Could the wires you tested be
used as fuse wire?
......................................
5 What current could you
use each one for?
.......................................
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Discoveries in electricity
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Teacher
activity notes
Type
Purpose
Differentiation
ICT
Pupils find out about Galvani and Volta and present their findings as a slide show
or leaflet.
Core
Running the activity
Divide the class into ability-matched groups if appropriate. Set them a clear time
limit for gathering information.
This activity could spread over two lessons and a homework. Decide what
resources will be available for research. Check whether all pupils can use the
internet, or move the class to the library if necessary.
Decide whether the output is to be in the form of a MS PowerPoint slide show or
a leaflet, and if the latter, whether it is to be word processed or not. Decide how
the results of the pupils’ work will be displayed to the rest of the class.
The following websites may be useful:
University of Idaho Department of Chemistry – Galvani
The Italian-American Website of New York – Volta
Electrochemistry pages – Galvani
The Great Idea Finder – Story of the Electric Battery
The Great Idea Finder – Volta
Other relevant material
Access to a computer connected to the internet, preferably with MS Word,
PowerPoint and a printer.
Skill sheet 4: Web searches
Skill sheet 19: Writing frame: Research
ICT opportinities
There are opportunities for pupils to carry out an internet search, store
information as Word files and present their findings as a PowerPoint slide show or
word-processed leaflet.
Pitfalls
An overabundance of information could cause pupils to lose sight of their aim in
the activity.
Answers
1 He passed current through frogs’ legs.
2 They carry messages as electric pulses.
3 An electric current causes our muscles to twitch.
4 It was a primitive battery.
5 Batteries.
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Discoveries in electricity
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Activity
Core
You are going to use books and the internet to research the work
of Luigi Galvani and Alessandro Volta. You will then prepare a
presentation about their discoveries.
^ _ Obtaining evidence
UG LP 1
TN
2
Find out as much as you can about your topic. Your teacher will
tell you how much time you have to do this. You may find it best
to save what you find out on a computer in Word files. Make sure
you give every file a clear title so you know what information you
have.
Try to find out the answers to the questions below for each
scientist. This will help you when you come to write your
presentation.
1 What is the connection between Galvani and frogs?
2 What does Galvani’s experiment tell us about the way nerves
carry messages to muscles?
3 How does Galvani’s experiment help us to understand the effects
of an electric current on humans?
4 Just over 200 years ago Alessandro Volta invented his ‘voltaic
pile’. What was it?
5 What do we use today that is based on Volta’s ‘voltaic pile’?
Presenting the evidence
3
Decide whether you are going to:
● print a leaflet or
● make a slide show.
Use the information you have found to make your leaflet or slide
show.
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Electrical energy
Plenaries
Suggested alternative plenary activities (5–10 minutes)
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Review learning
Sharing responses
Group feedback
Brainstorming
Looking ahead
Pupils describe how a
circuit works.
Whole-class discussion of
responses on energy
transfers in Activity J1a.
Groups of pupils compare
and discuss their answers
from Activity J1b.
Will it, won’t it?
Pupils suggest what life
would be like with no
electricity.
Review learning
● Pupils describe in words how a circuit works. They also
use a circuit diagram to represent what happens and an
energy transfer diagram to represent the energy
transfers taking place.
Sharing responses
● Write the words on the right on the board.
● Allocate one activity from Activity J1a to each pair of
pupils to describe to the others. Pupils should describe
the energy transfers taking place, using as many of the
key words on the board as they can. They summarise
the change using energy transfer diagrams. Lower
attaining pupils may need prompts, such as the teacher
providing the number of stages involved and building
up the transfer on the board as the pupils work through
what they saw and what that indicates in terms of
energy transfers.
Words
Chemical energy, electrical energy,
energy, energy transfer, light energy, heat
energy, sound energy, movement energy
Group feedback
● Pupils describe what effect the combinations of
switches have on the circuit.
● Ask pupils to suggest why we use the terms open and
closed to describe the behaviour of a switch rather than
‘on’ or ‘off’. (In everyday language we tend to say
‘switch the light on’ or ‘turn the light off’.)
Brainstorming
● Pupils decide if a circuit presented to them will or
won’t work. They justify their response.
➔ Pupil sheet
● Pupils can respond by writing yes/no on miniwhiteboards or by raising a hand for yes, or not for no.
● As an alternative, use a ‘traffic light’ system for
responding. Give pupils green cards to hold up for yes,
and red cards for no. (You can also use amber cards for
‘not sure’.)
Looking ahead
● Pupils suggest the consequences of having no electricity
for one day, one month or one year.
● They share their ideas in a class discussion.
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Plenaries
Electrical energy
J1
Brainstorming
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Decide which of these circuits will work. Give your reasons in each case.
a
UG LP
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b
c
d
e
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Current affairs
Plenaries
Suggested alternative plenary activities (5–10 minutes)
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UG LP
Review learning
Sharing responses
Group feedback
Word game
Looking ahead
How to measure current in
an electrical circuit.
Whole-class discussion
of responses from
Activity J2a.
Groups of pupils compare
and discuss their answers
from Activity J2b.
Pupils discuss word pairs.
Ask pupils to suggest
alternative ways of
connecting components.
Review learning
● Pupils describe how to measure current flow using an
ammeter. They could use a flow chart, a cartoon strip
or put the written statements on the Pupil sheet into
the correct sequence.
➔ Pupil sheet
Sharing responses
● Ask pupils to compare the data they collected in the
activity.
● Discuss what the pattern in the data shows about
current flow.
● Suggest how we can use the idea of water flowing to
explain the data about current.
● Discuss where the current comes from.
Group feedback
● Ask pupils to summarise in a sentence what they think
is the relationship between the number of cells in a
circuit and the current.
● Ask them to say what evidence they have from the
activity to suggest this.
● Discuss whether this evidence is supported by the
findings from all groups.
Word game
● Pupils discuss the word pairs (see right). They draw out
what the two words have in common and how they
differ. They could also identify where the word has a
different meaning in science and in everyday life.
Word pairs
Cell and battery
Electrical energy and electrical current
Voltage and amps
Circuit and current
Looking ahead
● Ask pupils to draw different circuit diagrams using the
list of components on the right.
● Ask pupils to show their suggestions and summarise the
suggestions on the board.
Components
Three cells, two lamps, one switch and
connector wires
● Ask which suggestions provide only one route/loop for
the current to flow and which provide more than one
route/loop for the current to flow.
● Ask pupils to suggest how the same components
behave differently in the circuit that provides only one
route for the current flow compared to the circuit that
has more than one route.
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Current affairs
J2
M
6
Plenaries
Review learning
p
?
t
u
^ _
Put these sentences in order to describe how to use an ammeter to
measure the current in a circuit.
1
UG LP
2
3
TN
4
5
6
Track round the circuit from the pole side of the cell/battery
until you reach the first component that will connect directly to
the ammeter.
First set up your circuit.
Decide between which two components in the circuit you want
to place the ammeter.
Connect the remaining terminal of the ammeter to the
component on the other side of it.
Locate the pole side of the cell/battery.
Connect the terminal of the ammeter to this component.
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Sheet 1 of 1
Current affairs
J2
Plenaries
Review learning
Put these sentences in order to describe how to use an ammeter to
measure the current in a circuit.
1
2
3
4
5
6
Track round the circuit from the pole side of the cell/battery
until you reach the first component that will connect directly to
the ammeter.
First set up your circuit.
Decide between which two components in the circuit you want
to place the ammeter.
Connect the remaining terminal of the ammeter to the
component on the other side of it.
Locate the pole side of the cell/battery.
Connect the terminal of the ammeter to this component.
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6
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J3
M
Different circuits
Plenaries
Suggested alternative plenary activities (5–10 minutes)
p
?
t
u
^ _
UG LP
Review learning
Sharing responses
Group feedback
Word game
Looking ahead
Pupils describe current
flow in series and parallel
circuits.
Whole-class discussion
of conclusions from
Activity J3a.
Groups of pupils compare
and discuss their solutions
from Activity J3b.
To check progress pupils
play dominoes about
electricity.
Pupils suggest strengths
and limitations of water
flow model of current flow.
Review learning
● Write the words (see right) on the board.
● Ask pupils to use these words to help them describe what
they have learnt about the current flowing in any series
circuit and the current flowing in any parallel circuit
Words
Parallel, series, circuit, current flow, the
same, greater, less than, ammeter reading,
resistance.
Sharing responses
● Ask pupils to summarise the pattern in the current
readings in series circuits and in parallel circuits.
● Help pupils to identify the differences in readings
between the series and parallel circuits
● Ask pupils to suggest what has happened to the current
in the parallel circuit.
● Help pupils to describe how the model of current flow
can explain what they have observed.
Group feedback
● Pupils present their circuit diagrams (either by building
the circuit for others to see or by using a circuit
diagram on the OHT/board).
● Pupils compare their circuits by looking at what is the
same and what is different.
● Ask pupils to describe how the current flow model
explains how their circuit works.
Word game
● Pupils play dominoes using the dominoes from the
Pupil sheet.
➔ Pupil sheet
● Two players draw five cards each. The rest are left in a
pile face downwards. The top card is turned over and
placed on the desk to start the game. Player one matches
one of his or her cards to either end of the starting
domino. Then player two takes his or her go. If either
player cannot go then that player must take an
additional card from the pile. The game is over when
one player has no cards left.
Looking ahead
● Ask pupils to suggest one strength of the water flow
model of current flow and one weakness.
● Put all the suggestions on the board and summarise the
main points.
● Pupils could suggest a model of their own to help
explain how current flows.
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Sheet 1 of 1
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A
ⴙ
ⴚ
Electric circuit
Parallel
circuit
Positive
terminal
Closed switch
Amp (A)
Safety device
for a circuit
Fuse
240 V
Voltage
of mains
electricity
Stops an
electrical
current
flowing
Examples of
electrical
insulators
Fault
Makes it
harder for
electricity to
flow
This can
happen when
the current is
too high
Bulb blows
Resistance
Series
circuit
^ _
Unit of
current
Volta
Different circuits
Unit of
voltage
Volt (V)
Open switch
Plastic and
rubber
Italian inventor
of electric
battery
TN
Electrical
conductance
UG LP
Ammeter
Property of
metals
u
Light bulb
t
Negative
terminal
?
Cell
J3
Path that
electric current
will flow
through
p
Word game
Print current page (1 page)
6
Plenaries
M
Sheet 1 of 1
6
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J4
M
Models of electricity – Think
about
p
?
Suggested alternative plenary activities (5–10 minutes)
t
u
Group feedback
Bridging to other topics
Pupils discuss how the different models
helped them to understand electricity
better.
Pupils discuss how the use of scientific
models will help them in other topics.
^ _
UG LP
Plenaries
Group feedback
● Pupils describe how the models help them visualise
what is happening in the electric circuit.
● They discuss how the coal truck model and the
matches model are different from the water flow model
and how they are similar.
● Present them with a circuit that they have not met
before including an open switch. Ask pupils to predict
what is likely to happen once the switch is closed,
using a model of electricity.
● Remind them that a model allows us to make
suggestions/predictions about new and unexplored
contexts.
Bridging to other topics
● Explain that scientists use models to help them
understand many different situations that they can’t
easily see or touch.
● Give some examples of other models they will use.
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Examples
7A Cells that make up all living things
7L To understand the solar system
7G How the small particles that make
matter behave
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6
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J5
M
Electrical hazards
Plenaries
Suggested alternative plenary activities (5–10 minutes)
p
?
t
u
^ _
UG LP
Review learning
Sharing responses
Group feedback
Word game
Looking back
Pupils summarise key
points about hazards and
electricity.
Whole-class discussion of
presentations from
Activity J5c.
Groups of pupils compare
and discuss their solutions
from Activity J5a.
Check progress by playing
‘bingo’ with key words
from the unit.
Pupils revise and
consolidate knowledge from
the unit.
Review learning
● Each pupil summarises what he or she has learnt about
hazards and electricity in two or three key points. Carry
out a class scan and ask individual pupils to share their
points.
● Ask pupils to check their key points with the learning
objectives for the lesson.
Sharing responses
● Ask each group of pupils to present their PowerPoint
show or leaflet.
● Other pairs/groups ask questions about the work.
Group feedback
Questions
How did the scientists explain their
findings?
How did the scientists use their discovery?
What was the reaction of society to their
work?
● Pupils present their circuit diagrams (either by building
the circuit for others to see or by using a circuit
diagram on the OHT/board). Ask them to compare
what is the same and what is different about their
circuits.
● Pupils list similarities and differences between circuits
in Christmas tree lights and a ring main.
● Ask pupils to describe how the current flow model
explains how their circuit works.
Word game
● Pupils select nine words from the table to write into
their bingo grid.
➔ Teacher sheet
➔ Pupil sheet
● Read out definitions from the Teacher sheet in any
order. Pupils match these to their chosen words.
The game is over when a pupil can strike out a line.
● The pupil has to recall the definitions as he or she
reads out each word back to the class to check the
winning line.
Looking back
● Pupils revise and consolidate knowledge from the unit.
They can use the Unit map, Pupil check list or the Test
yourself questions.
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➔ Unit map
➔ Pupil check list
➔ Test yourself
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J5
M
Plenaries
Electrical hazards
Word game
p
?
Bingo!
t
u
Choose nine words from the list below and write them in the
empty grid.
^ _
UG LP
TN TS
resistance
fuse
amp
cell
er
energy transf
parallel
current
ring main
volt
series
fuse
battery
Cross out each word when you hear the teacher read out its
definition.
Shout ‘BINGO!’ when you have crossed out a line of three words on
the card.
The line can be across, down or diagonally.
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J5
M
Electrical hazards
Plenaries
Word game
p
?
t
u
^ _
Read out the definitions below in any order.
This reduces the amount of flow in a circuit.
[resistance]
A protective device which melts if too great an electric
current flows through it.
[fuse]
UG LP The unit of current.
[amp]
TN PS The unit of voltage.
[volt]
Describes the movement of energy from one place to
another.
[energy transfer]
The amount of flow in a circuit each second.
[current]
A circuit with more than one loop.
[parallel]
Describes the electric circuits used in our homes.
[ring main]
A circuit with just one loop.
[series]
Uses a chemical reaction to push electricity around a
circuit.
[cell]
A collection of two or more cells, provides the push in an
electric circuit.
[battery]
A safety device to prevent electric shocks.
[fuse]
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J1
M
W
p
?
t
u
Specials
Electrical energy
1 Match the words to their meanings.
This is the energy
source for the circuit.
switch
^ _
UG LP
TN
You need to close this
to complete the circuit!
circuit
This must be complete (no gaps)
for electricity to flow round it.
cell
2 When a lamp is switched on it changes electrical energy
into two other kinds of energy.
Choose some of these words to fill in the gaps.
electrical
t
movemen
cell
lamp
chemical
light
sound
heat
The cell has a store of
............................................
energy
The wires transfer ..................................................
energy from the ............................................
to the ............................................ .
The lamp transfers the energy as
...........................................
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and ............................................ energy.
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J1
M
W
p
?
t
u
Specials
Electrical energy (continued)
3 Look at the circuits. Some of them won’t work!
A
ⴙ
ⴚ
ⴙ
B
ⴚ
^ _
UG LP
TN
D
C
ⴙ
ⴚ
ⴚ
ⴙ
a Cellls should be connected:
negative to negative
positive to positive
Tick the
box.
positive to negative.
b Which circuits are correct? .............................................
c What is wrong with the incorrect circuits?
.........................................................................................................................................................................................................
.........................................................................................................................................................................................................
.........................................................................................................................................................................................................
d What is a battery? Circle the correct answer.
of
a kind
chicken
two or
more c
ell
joined
togeth s
er
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ll
one ce
wn
on its o
Sheet 2 of 3
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J1
M
W
t
u
6
Electrical energy (continued)
Specials
4 These sentences are about how the lamp gives
out light. They’re all mixed up! Write numbers in
p ?
the boxes to put them in order.
^ _
The cell is a store of energy.
UG LP
TN
The hot wire glows and gives out light.
When the cell is connected to the lamp, electricity flows.
The electricity carries energy to the wire.
The energy makes the wire hot.
5 Cross out the wrong words. Underline the right words.
Energy goes into / out of the circuit at the cell.
Cells with a high / low voltage store more energy.
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J2
M
W
p
?
t
u
Specials
Current affairs
1 Look at this circuit.
ⴚ
ⴙ
^ _
UG LP
TN
a Put your finger on the cell where the + sign is.
Trace around the circuit to the other side of the battery
where the – sign is. This is the path the electric
current takes to make the lamp light up.
b Draw arrows on the circuit to show how the electric
current flows around it.
2 a Cross out the wrong words. Underline the
right words.
To measure the current flowing I can use
an ammeter / voltmeter. Current is
measured in joules / amps / volts.
b Where would you put an ammeter to
measure the current? Draw an ammeter
on the circuit to show where you would put it.
3 Write true or false for each sentence.
a The more cells there are in a circuit, the bigger the push
and the bigger the current. ..........................
b The current is not used up as it flows around the circuit. ..........................
c The current is the same on both sides of a lamp. ..........................
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M
W
p
?
t
u
Specials
Different circuits
J3
1 Label these circuits series or parallel.
a
b
^ _
UG LP
TN
..............................................
c
..............................................
d
A
A
..............................................
..............................................
2 Cross out the wrong words. Underline the right words.
a In a series / parallel circuit, the lamps are in different
loops.
b In a series / parallel circuit, the lamps are side by
side.
c When two lamps are connected in series, they shine
more / less brightly than one lamp alone in a circuit.
d When two lamps are connected in series / parallel,
they shine as brightly as one lamp alone in a circuit.
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Different circuits (continued)
J3
M
W
p
?
t
u
Specials
3 Look at these two circuits.
A
B
^ _
UG LP
TN
a Which circuit shows two lamps connected in series? .............
b Which circuit shows two lamps connected in parallel? .............
c Will the lamps be brighter in circuit A or circuit B? .............
d If you unscrew one lamp in circuit A, what will happen to
the other lamp? Will it go out or will it stay on? ...............................................................
e If you unscrew one lamp in circuit B, what will happen to
the other lamp? Will it go out or will it stay on? ...............................................................
4 Write true or false for each sentence.
a In a series circuit, the current is different at different points. ..........................
b In a parallel circuit, the current is shared between the loops. ..........................
c If there is a high resistance, it is easy for the current to flow. ..........................
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J4
M
W
t
u
Specials
Models of electricity
1 You know some important things about electricity.
Can you pick them out of this list?
p ?
^ _
UG LP
TN
Electricity carries energy to make things work.
Tick the
boxes to show
the right
ones.
There is no energy in electricity.
You need a complete circuit to make a lamp light.
A lamp will light if there is a break in the circuit.
The current is the same on both sides of the lamp.
The current is different in different places in a circuit.
2 Look at Sheet 2. It shows the coal truck model of electricity.
a Match the parts of the model to the electrical ideas.
coal mine
the lamp
coal
the cell
railway line
the energy
power station
the circuit
b The trucks move faster. The current …
… decreases
… increases
Tick the
box to show
the right
answer.
… stays the same.
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J4
M
W
p
?
Models of electricity (continued)
Specials
The coal truck model
The coal trucks move around the railway. They pick up
t u coal from the mine. They drop the coal at the power
^ _ station. They go back to the mine for more coal. The
trucks can move quickly or slowly.
UG LP
TN
mine
power station
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6
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J5
M
Specials
Electrical hazards
W
1 Sunil has just put new batteries
into his bike light, but it’s not working.
p ?
He thinks it’s broken. What should
t u
he do to check it out? Tick all
^ _
the correct things he could do.
UG LP
TN
Throw the light away and buy a new one.
Check the batteries are put in the right way round.
Hit the light to see if that will make it work.
Try a new lamp in the light.
Check the wires to see that they are not loose.
2 Use words from this list to complete the sentences.
series
stay on
go out
ring main
parallel
The electrical circuit in a house is called a ...................................................
The lamps in this circuit are all connected in ............................................
If one lamp is switched off or goes out, the others ...................................................
4 Write true or false for each sentence.
a Mains electricity contains more energy than the
electricity from a cell. ..........................
b If you have an electric shock, it cannot stop your heart
beating. ..........................
c Not all plugs on electrical appliances have a fuse. ..........................
d If too much electricity flows to the appliance, the fuse
melts and breaks the circuit. ..........................
e If too much electricity flows through wires, they do not
melt and catch fire. ..........................
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J
M
p
?
t
u
^ _
UG
Electrical circuits
Specials answers
J1 Electrical energy
J4 Models of electricity
1 switch – You need to close this to complete the
circuit.
circuit – This must be complete (no gaps) for
electricity to flow round it.
cell – This is the energy source for the circuit.
2 The cell has a store of chemical energy. The
wires transfer electrical energy from the cell to
the lamp. The lamp transfers the energy as heat
and light energy.
3 a Cells should be connected positive to
negative.
b circuit A
c Cells are connected positive to positive or
negative to negative.
d A battery is two or more cells joined
together.
4 1, 5, 2, 3, 4
5 Energy goes into the circuit at the cell. Cells
with high voltage store more energy.
1 Electricity carries energy to make things work.
You need a complete circuit to make a lamp
light.
The current is the same on both sides of the
lamp.
2 a coal mine the cell, coal the energy,
railway line the circuit,
power station the lamp
b increases
J5 Electrical hazards
1 Check the batteries are put in the right way
round.
Try a new lamp in the light.
Check the wires to see that they are not loose.
2 ring main, parallel, stay on
3 a true
b false
c false
d true
e false
J2 Current affairs
1 a Pupils trace from positive to negative along
the wires.
b Arrows drawn along wires from positive to
negative.
2 a To measure the current flowing I can use an
ammeter. Current is measured in amps.
b Ammeter drawn (circle enclosing an upper
case A) anywhere between lamp and cell.
3 a true
b true
c true
J3 Different circuits
1 a series b parallel
c parallel d series
2 a In a parallel circuit the lamps are in different
loops.
b In a series circuit the lamps are side by side.
c When two lamps are connected in series,
they shine less brightly than one lamp alone
in a circuit.
d When two lamps are connected in parallel,
they shine as brightly as one lamp alone in a
circuit.
3 a B
b A
c A
d It will stay on.
e It will go out.
4 a false
b true
c false
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Homework
Electrical energy
J1
M
W
HELP
p
?
1 Copy and complete these sentences using the words below.
t
u
voltage
cell
lamp
^ _
UG LP
a Energy goes into the circuit at the ...................................... .
TN
b
......................................
makes the current flow.
c Energy goes out of the circuit at the ...................................... .
2 Look at the circuit opposite.
Copy and complete the table to show which
lamps will light as you close the switches.
The first one has been done for you.
Switches closed
Lamps lit
X only
none
X
1
Y
X and Y
X and Z
2
Y and Z
3
X, Y and Z
Z
CORE
3 a Draw the circuit symbol for:
i a single cell
ii a lamp (bulb).
b Use the circuit symbols to draw a circuit diagram for
the circuit opposite.
c Draw the circuit diagram for the circuit again, but this
time add another component (part) that could be used
to turn the lamp on and off.
d Copy and complete this
energy transfer diagram
for the circuit.
...................................... energy
chemical
energy
stored in
the cell
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lamp
...................................... energy
in the wires
...................................... energy
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6
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M
W
p
?
t
u
Homework
Electrical energy (continued)
J1
4 Look at the circuit diagrams below. The lamp is off in all the circuits.
For each circuit, explain why the lamp is off.
A
B
C
^ _
UG LP
TN
EXTENSION
5 A battery contains four cells. Each cell provides 1.5 V of electrical
energy when it is new.
a What is the maximum voltage provided by this battery?
b The battery was used to drive a radio-controlled toy. After two
hours of constant use, the toy stopped. Explain why.
c In a different toy, the new battery provided 12 V of electrical energy.
Each cell was the same as those in the battery in part a. How many
cells are in this 12 V battery?
d Copy and complete the table by matching each electrical item
with the most appropriate cell in the table.
● Digital watch: needs only a small
● Car : needs a large energy burst to
energy transfer but it is fiddly to
start the engine.
change the cell.
● Camera: needs a low energy transfer
● Radio-controlled car : does not need a
to work the light meter, and a large
large energy transfer but batteries run
energy transfer to charge up the flash
down quickly.
unit.
● Torch: needs a small energy transfer
only.
Type of cell
or battery
Characteristics
lithium cell
reliable and long lasting
mercury cell
expensive; can produce both short, highenergy transfers and long, low-energy transfers
lead–acid
battery
can be recharged; produces very large
energy transfers
dry cell
cheap; cannot be recharged; produces
only small energy transfers
Ni–Cad cell
can be recharged but produces only
small energy transfers and is expensive
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Electrical item
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Homework
Current affairs
J2
M
W
HELP
p
?
t
u
1 You sometimes see this symbol in a circuit: A
What piece of apparatus does the symbol stand for?
^ _ 2 Copy and complete these sentences, choosing from the words in
UG LP
TN
bold.
a The current/brightness in a circuit is measured in amps.
b The current in a circuit gets bigger/is used up/stays the
same as it goes through a lamp.
c In a simple circuit with one cell and one lamp, the current into
the lamp is bigger than/smaller than/the same as the
current out of the lamp.
3 Draw a circuit diagram showing a cell, a lamp and an ammeter
connected together.
CORE
4 Look at the diagram. Which part of an
electrical circuit do letters A to E stand
for? Choose from the words below.
cell
E
heat energy
transferred
to room
lamp
thermostat
B
pipes
light and hea
t energy
transferred fro
m lamp
crocodile clip
s
C
radiator
current
A
boiler
wires
D
water
flow
5 Look at this circuit diagram.
a You want to measure the current flowing
through lamp B. Redraw the circuit
diagram showing where you would
put the ammeter.
b Redraw the diagram again with the
ammeter in a different position that
would give the same reading.
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A
B
C
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J2
M
W
EXTENSION
p
?
t
u
6 This table shows how the current varies
with the number of cells in a circuit.
The cells are identical.
^ _
UG LP
TN
Homework
Current affairs (continued)
Number of cells
Current in amps
1
0.1
2
0.2
3
0.3
4
0.4
5
0.5
a Why does the current increase as the
number of cells increases?
b Why does the current increase in
equal steps?
c What would the current be if you
connected 10 of these identical cells together in the circuit?
7 Helen suggested this model to help her to explain how a circuit
works.
pump
A
turbine
water
pumped up
to go round
again
B
direction
of turn
water
flowing
a What type of energy is stored in the water at point A?
b What type of energy is transferred to the turbine at point B?
c Is there anything in the model that represents the current in a
real circuit? If so, what is it and how does it represent current?
d Is there something that represents a cell? If so, what is it and
how does it represent a cell?
e Explain why the turbine represents a lamp in a real circuit.
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Homework
Different circuits
J3
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HELP
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1 Copy and complete these sentences, choosing from the words in
bold.
^ _
UG LP
TN
a A thin piece of wire slows the current down more/less than a
thick piece of wire.
b If a piece of wire slows the current down, it has a high
resistance/current.
c A thick piece of wire has a low resistance, so it is easy/hard for
the current to flow.
2 Five circuit diagrams are shown below.
A
B
D
C
E
Copy and complete the table to show which circuits are series and
which are parallel.
Series circuits
Parallel circuits
CORE
3 Look at the diagrams in question 2.
a Will the lamps be brighter in circuit A or circuit B?
b In which circuit will the lamps have the same brightness as in
circuit B?
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Homework
Different circuits (continued)
J3
4 Some circuit diagrams are shown below. Think about them
carefully, then copy and complete the table to show the current
measured by each ammeter.
^ _
UG LP
TN
A1
A3
A4
Ammeter
Current
in amps
A1
1.5
A7
A2
A3
A5
A6
A2
A4
0.6
A5
0.2
A6
A7
A9
A8
A12
A8
3.0
A9
A10
A10
1.0
A11
A12
A11
EXTENSION
5 Tong’s dad owns a Chinese restaurant. It has a large model dragon
in the centre of the room that is lit up by a bulb inside it. Tong’s
dad likes to turn the lights down gradually during the evening to
add a bit of atmosphere.
a What could he add into the dragon lighting circuit to do this?
Explain how this would make the bulb gradually dimmer.
One busy evening the bulb failed, so Tong’s dad replaced it with a
new one. The new bulb was very dim and the dragon looked
rather pathetic, instead of rather spectacular.
b Suggest what mistake Tong’s dad might have made when he
replaced the bulb, and explain why this made the new bulb
shine less brightly. Use the words ‘resistance’ and ‘current’ in
your answer.
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Electrical hazards
J5
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1 Look at the circuits below. Some will work. Some have a fault and
won’t work.
^ _
A
B
C
UG LP
TN
D
E
Copy and complete the table below.
Circuit
Will the circuit work?
If not, what is the fault?
A
B
C
D
E
2 Copy and complete these sentences.
a A fuse is an electrical safety device that melts if …
b Fuse wires have a ...................................... resistance.
c When a fuse wire melts, the electrical energy is transferred as
......................................
energy and ...................................... energy.
d If you get a shock from mains electricity, it can kill because it …
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Electrical hazards (continued)
J5
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CORE
p
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3 a Draw a circuit, using only a cell, a lamp and connecting wires,
that you could use to find out whether components were faulty
or good.
^ _
UG LP
TN
b How would the circuit tell you if a component was:
i faulty?
ii good?
c Sanjay built a fault-finding circuit and used it to test the
headlight bulbs from his radio-controlled model car.
Copy and complete the table below, using the word faulty or
good in the last column.
Car bulb
Fault-finder bulb
left
on
right
off
State of car bulb
d Even with one faulty headlight bulb, the other model car
headlight still worked. What kind of circuit had been used to
connect the model car’s headlights?
4 a The red stop lights on a car are connected in a parallel circuit.
Explain why a series circuit is not used for these lights.
b In a hair dryer, the heater and the fan might be connected in a
series circuit. Suggest why this is useful if the fan motor stops
working.
c It is not helpful to connect fairy lights together using a series
circuit. Explain why not.
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Electrical hazards (continued)
J5
EXTENSION
Look at this circuit carefully. It contains something
you may not have seen before. If the electricity can
t u
bypass a lamp without having to go through it, then
^ _ it will. In this circuit the electricity will go along the
UG LP simple wire and not through the lamp. This means
that the lamp will not light up. This idea is important
TN
in the questions below.
5 Look at this circuit diagram.
Which lamps will be lit if:
a only switch X is closed (on)?
X
b only switch Y is closed (on)?
c both switches X and Y are
closed (on)?
A
B
Y
C
D
6 Look carefully at the circuit diagram below.
E
H
F
G
a You want to add a switch or switches that will allow lamps F, G
and H to be turned off whilst lamp E stays on. Redraw the circuit
diagram, adding the switch or switches you need.
b You would like to be able to turn lamp G on and off independently
of the other three lamps. Draw the circuit diagram again and add
one switch only to show how this could be done.
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Electrical energy
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HELP
Question
Answer
1 a
Energy goes into the circuit at the cell.
1
b
Voltage makes the current flow.
1
c
Energy goes out of the circuit at the lamp.
Underscores show answers; other text copied by pupils.
1
X and Y: 1
X and Z: 2 and 3
Y and Z: none
X, Y and Z: 1, 2 and 3
1
1
1
1
^ _
UG LP
Homework
mark scheme
2
HM
Mark
Total for Help
7
CORE
Question
Answer
Mark
3 a i
1
ii
1
b
2
One mark for correct circuit diagram; one mark for using a ruler and drawing
with no breaks.
c
1
One mark for the correct symbol for a switch inserted somewhere between the cell
and the lamp.
d
light energy
Chemical energy
stored in the
cell
electrical energy
in the wires
lamp
heat energy
3
Underscores show answers; other text copied by pupils.
One mark for each correct answer.
4
A: one cell connected the wrong way round
B: switch open or off or not closed or not on
C: break in (top left of) circuit or circuit is not complete
1
1
1
Total for Core
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^ _
UG LP
HM
Homework
mark scheme
Electrical energy (continued)
J1
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EXTENSION
Question
Answer
Mark
5 a
6V
1
b
All or most of the energy stored in the battery had been transferred.
1
c
8
1
d
Lithium cell: digital watch
Mercury cell: camera
Lead–acid battery: car
Dry cell: torch
Ni–Cad cell: radio-controlled car
1
1
1
1
1
Total for Extension
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Current affairs
J2
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HELP
Question
Answer
Mark
1
Ammeter
1
2 a
The current in a circuit is measured in amps.
1
b
The current in a circuit stays the same as it goes through a lamp.
1
c
In a simple circuit with one cell and one lamp, the current into the lamp is
the same as the current out of the lamp.
1
^ _
UG LP
HM
Homework
mark scheme
Underscores show answers; other text copied by pupils.
3
A
1
One mark for the ammeter anywhere between the lamp and the cell.
Total for Help
5
CORE
Question
Answer
Mark
4
A cell
B wires
C lamp
D current
E light and heat energy transferred from lamp
1
1
1
1
1
5 a
A
B
A
C
1
One mark for the ammeter either side of lamp B.
b
A
B
A
C
1
One mark for the ammeter the opposite side of lamp B.
Total for Core
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Current affairs (continued)
J2
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^ _
UG LP
HM
6
Homework
mark scheme
EXTENSION
Question
Answer
Mark
6 a
Increasing the number of cells puts more (electrical) energy into the circuit,
so the current increases.
Accept equivalent answers.
1
b
Each identical cell adds the same amount of extra energy.
Accept equivalent answers.
1
c
1.0 A
1
Gravitational
1
b
Kinetic
1
c
The water
It flows round the system and goes back to where it started.
1
1
d
The pump
It supplies energy to the water.
1
1
e
It transfers energy from the flowing water.
A lamp transfers energy from the flowing current.
1
1
7 a
Total for Extension
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HELP
Question
Answer
1 a
A thin piece of wire slows the current down more than a thick piece of wire.
1
b
If a piece of wire slows the current down, it has a high resistance.
1
c
A thick piece of wire has a low resistance, so it is easy for the current to flow.
Underscores show answers; other text copied by pupils.
1
^ _
UG LP
Homework
mark scheme
Different circuits
J3
M
6
2
Mark
Series circuits: A, C
Parallel circuits: B, D, E
HM
1, 1
1, 1, 1
Total for Help
8
CORE
Question
Answer
Mark
3 a
B
1
b
D
1
A1 1.5, A2 1.5, A3 1.5
A4 0.6, A5 0.2, A6 0.4, A7 0.6
A8 3.0, A9 3.0, A10 1.0, A11 2.0, A12 3.0
Underscores show answers; other text copied by pupils.
4
1, 1
1, 1
1, 1, 1
Total for Core
9
EXTENSION
Question
Answer
5 a
A dimmer switch or length of wire with a high resistance
Turning down the dimmer switch or moving a connection along
the resistance wire includes more of the resistance wire in the circuit,
increasing the resistance of the circuit and reducing the current or
making the bulb less bright.
1
He used a bulb with a higher resistance,
so it reduced the current a lot more, making the bulb less bright.
1
1
b
Mark
1
1
Total for Extension
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HELP
Question
Answer
1
A: no, one cell is the wrong way round or cells are back to back
B: yes
C: no, the wire is not connected to the lamp
D: yes
E: no, both wires are connected to the same end of the cell
Accept equivalent answers.
2 a
A fuse is an electrical safety device that melts if the current gets too high
or there is a fault.
1
b
Fuse wires have a high resistance.
1
c
When a fuse wire melts, the electrical energy is transferred as heat energy
and light energy.
Answers can be in either order.
1
1
d
If you get a shock from mains electricity, it can kill because it stops the heart
beating.
Underscores show answers; other text copied by pupils.
^ _
UG LP
HM
Homework
mark scheme
Electrical hazards
J5
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6
Mark
1
1
1
1
1
1
Total for Help
10
CORE
Question
Answer
3 a
Series circuit with cell, bulb and two unconnected wire endings.
Wires (except the unconnected ends) drawn with a ruler.
1
1
b i
ii
The lamp would not light.
The lamp would light.
1
1
c
Left: good
Right: faulty
1
1
d
Parallel
1
In a series circuit, both lamps would fail if one bulb breaks, but in a parallel
circuit, one still works.
1
b
If the fan stops working, so does the heater, preventing overheating.
1
c
If one bulb fails, all the lamps go out, so you don’t know which one to replace
or if one bulb comes loose, all the lamps go out.
1
4 a
Mark
Total for Core
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Electrical hazards (continued)
J5
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^ _
UG LP
Homework
mark scheme
EXTENSION
Question
Answer
Mark
5 a
A, B, C and D
1
b
C and D
1
c
B, C and D
1
6 a
E
HM
H
F
G
1
One mark for the circuit redrawn with a switch at any point below the connection
points for lamp E.
b
E
H
F
G
1
One mark for the circuit redrawn with a switch in a wire running from between
bulbs F and G to between bulbs G and H.
Total for Extension
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Electrical circuits
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6
Transition quiz
Draw a line between each name and its correct symbol.
a battery or cell
^ _
UG
b bulb or lamp
TN
c switch
d wire
2
Look at these circuits. None of lamps will work. Circle where the
fault is in each circuit.
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Electrical circuits
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Transition
worksheet
Circuit X is shown below.
ⴙ
^ _
ⴚ
ⴙ
ⴚ
UG
TN
circuit X
Redraw circuit X using these symbols.
2
Look at this circuit.
a Which lamp or lamps will light
when you close switches
B and C? ...................................... .
b Which switch or switches do
you need to close to make
lamp 1 light? ...................................... .
c Which lamps will light
if you close only switch
C? ...................................... .
1
C
A
2
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B
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Test yourself
Electrical circuits
1 Complete this table.
p
?
t
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Symbol
Component
^ _
cell
UG
TN
ammeter
2 Draw a circuit diagram for each circuit.
What name is given to each type of circuit?
ⴙ
ⴙ
ⴚ
......................................
circuit
ⴚ
......................................
circuit
3 Tick the lamps that will light up.
4 Complete these sentences by crossing out the wrong words.
a In a series circuit, as more lamps are added the lamps
get brighter/get dimmer/stay the same brightness
and the current through each lamp increases/decreases/stays the same.
b In a parallel circuit, as more lamps are added the lamps
get brighter/get dimmer/stay the same brightness
and the current through each lamp increases/decreases/stays the same.
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Test yourself
Electrical circuits (continued)
J
5 Write in the missing reading for each ammeter opposite.
p
?
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X
..........................
Y
..........................
X
A
2.5 A
A
1A
A
6 Bob has a battery-operated electric toothbrush which has
^ _
stopped working. List three things for him to check to see
what is wrong.
UG
TN
A
............................................................................................................................................
Y
A
0.5 A
............................................................................................................................................
............................................................................................................................................
7 You are given a box of components to sort out
which are working and which are broken.
Circuit diagram
a Draw a circuit diagram for a test circuit with
a lamp, that you could use to test lamps,
switches and connecting wires from the box.
b How would you use your circuit to find out if a lamp was faulty?
......................................................................................................................................................................
......................................................................................................................................................................
c How would you use your circuit to find out if a wire was faulty?
......................................................................................................................................................................
......................................................................................................................................................................
8 When a battery goes flat, what is used up? Circle the correct letter.
A energy
B current
C voltage
D mass
9 Complete these sentences.
In a cell, ...................................... energy is converted to ...................................... energy.
In a lamp, ...................................... energy is converted to ...................................... energy
and ...................................... energy.
10 Look at the circuit opposite. Circle the correct letter(s)
each time. Which lamp or lamps will light when:
a only switch A is closed?
X
Y
Z
b only switch B is closed?
X
Y
Z
c switches A and B are closed?
X
Y
Z
A
X
Y
B
Z
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11 Complete these sentences to explain how a fuse protects an
electrical appliance. Choose from the words below to fill the gaps.
wire
mends
^ _
current
UG
TN
Test yourself
Electrical circuits (continued)
J
low
high
stops
resistance
melt
breaks
A fuse contains a piece of ...................................... which has a higher ......................................
than the rest of the circuit. If the current gets too ...................................... , the fuse will
.......................................
This ...................................... the circuit so that the current
...................................... ,
protecting you from harm.
12 For a summer party, some friends are putting up a string of lights
in the garden. What will happen if a bulb blows:
a if the lights are wired in series? ...........................................................................
b if the lights are wired in parallel? .......................................................................
13 Which of these arrangements will give the brightest light from
the lamp? Circle the correct letter.
A
A
B
ⴚ
C
ⴙ
ⴙ
D
ⴚ
ⴚ
B
ⴙ
C
ⴙ
ⴚ
ⴙ
ⴙ
ⴚ
ⴚ
ⴙ
D
ⴚ
ⴙ
ⴚ
ⴙ
ⴚ
ⴚ
ⴙ
14 Some children are given three different pieces of wire, A, B and C.
They connect up a circuit like this. The table shows their results.
wires A, B, and C
connected in here
Wire
Lamp
A
dim
B
no light
C
bright
a Which piece of wire allows the current to pass through it easily?
b Which piece of wire has the highest resistance?
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.............
.............
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J
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Electrical circuits
Test yourself
Answers
1 Complete this table.
p
?
t
u
Symbol
Component
lamp or bulb
switch
^ _
UG
cell
TY
battery
A
ammeter
2 Draw a circuit diagram for each circuit.
What name is given to each type of circuit?
ⴙ
ⴙ
ⴚ
series
......................................
ⴚ
parallel
circuit
......................................
circuit
3 Tick the lamps that will light up.
✓
✓
✓
✓
✓
✓
4 Complete these sentences by crossing out the wrong words.
a In a series circuit, as more lamps are added the lamps
get brighter/get dimmer/stay the same brightness
and the current through each lamp increases/decreases/stays the same.
b In a parallel circuit, as more lamps are added the lamps
get brighter/get dimmer/stay the same brightness
and the current through each lamp increases/decreases/stays the same.
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Electrical circuits (continued)
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Test yourself
Answers
X
A
5 Write in the missing reading for each ammeter opposite.
p
?
t
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X
2.5 A
..........................
Y
1A
2.5 A
..........................
A
6 Bob has a battery-operated electric toothbrush which has
^ _
stopped working. List three things for him to check to see
what is wrong.
UG
Is the battery flat?
............................................................................................................................................
TY
Are the contacts to the battery wet/dirty/corroded?
............................................................................................................................................
1A
A
A
Y
A
0.5 A
Are the contacts to the switch wet/dirty/corroded/Does the switch work?
...............................................................................................................................................................................................................
7 You are given a box of components to sort out
which are working and which are broken.
Circuit diagram
a Draw a circuit diagram for a test circuit with
a lamp, that you could use to test lamps,
switches and connecting wires from the box.
test components in this gap
b How would you use your circuit to find out if a lamp was faulty?
Put the lamp in the gap to complete the circuit. If the lamps
............................................................................................................................................................................
light, it is working. If neither lamp lights, it is faulty.
............................................................................................................................................................................
c How would you use your circuit to find out if a wire was faulty?
Put the wire in the gap to complete the circuit. If the lamp
............................................................................................................................................................................
lights, the wire is working. If not, the wire is faulty.
............................................................................................................................................................................
8 When a battery goes flat, what is used up? Circle the correct letter.
A energy
B current
C voltage
D mass
9 Complete these sentences.
chemical energy is converted to ......................................
electrical energy.
In a cell, ......................................
electrical energy is converted to ............................................
light/heat energy
In a lamp, ......................................
heat/light energy.
and ............................................
10 Look at the circuit opposite. Circle the correct letter(s)
each time. Which lamp or lamps will light when:
a only switch A is closed?
X
Y
Z
b only switch B is closed?
X
Y
Z
c switches A and B are closed?
X
Y
Z
A
X
Y
B
Z
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Electrical circuits (continued)
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11 Complete these sentences to explain how a fuse protects an
electrical appliance. Choose from the words below to fill the gaps.
wire
mends
^ _
current
UG
TY
Test yourself
Answers
low
high
stops
resistance
melt
breaks
wire
resistance
A fuse contains a piece of ......................................
which has a higher ..............................................
high
than the rest of the circuit. If the current gets too ......................................
, the fuse will
breaks
melt
This ......................................
the circuit so that the current
stops
......................................
, protecting you from harm.
.......................................
12 For a summer party, some friends are putting up a string of lights
in the garden. What will happen if a bulb blows:
They will all go out.
a if the lights are wired in series? ...........................................................................
Only one will go out.
b if the lights are wired in parallel? .......................................................................
13 Which of these arrangements will give the brightest light from
the lamp? Circle the correct letter.
A
B
A
ⴚ
C
ⴙ
ⴙ
D
ⴚ
ⴚ
B
ⴙ
C
ⴙ
ⴚ
ⴙ
ⴙ
ⴚ
ⴚ
ⴙ
D
ⴚ
ⴙ
ⴚ
ⴙ
ⴚ
ⴚ
ⴙ
14 Some children are given three different pieces of wire, A, B and C.
They connect up a circuit like this. The table shows their results.
wires A, B, and C
connected in here
Wire
Lamp
A
dim
B
no light
C
bright
a Which piece of wire allows the current to pass through it easily?
b Which piece of wire has the highest resistance?
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C
.............
B
.............
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Electrical circuits
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End of unit test
Green
1 Here are some circuits. For each one say whether or not the bulb
will light when the switch is pressed.
a
ⴙ
b
ⴚ
ⴙ
2 marks
ⴚ
^ _
UG SS
MS ET
c
ⴙ
d
ⴚ
ⴙ
ⴚ
2 This table shows some symbols that are used to draw
circuit diagrams. Some names and symbols are missing.
Write the missing names a and b and draw
the missing symbols c and d.
a
A
resistor
4 marks
3 a What instrument is used to measure electric current?
b
c
lamp (bulb)
d
cell
1 mark
Look at the circuit diagrams.
8A A
A
2A
A
X
Y
A
A
4A
b What is the current measured at X?
1 mark
c What is the current measured at Y?
1 mark
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4 a Here are two ways of wiring
up a circuit with two lamps.
Circuit A is called a series
circuit.
^ _
What is the name given
to circuit B?
UG SS
MS ET
End of unit test
Green
A
B
1 mark
b One of the bulbs in this lamp
has blown and needs replacing.
i Which circuit, A or B,
shows how the bulbs
are wired up?
1 mark
ii Explain how you
decided this.
1 mark
5 Here are three circuits.
C
E
ⴙ
ⴚ
ⴙ
ⴙ
ⴚ
D
ⴙ
ⴚ
ⴙ
ⴚ
ⴚ
Which circuit is shown by this
circuit diagram?
1 mark
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6 Look at the circuit diagram. We can use a marble model to
represent this circuit.
H
H
M
Electrical circuits (continued)
HHHHHHH H H
J
End of unit test
Green
marble pusher
tube
H
HH
H
paddle
wheel
H H HHHHHHHHHHHH H H
H H HHHHHHHHHH
HHHHHHHHHHHHHHHHHHHHHHHHHHHHHH
H H H H
HHH
a What in the model represents the current?
1 mark
b When the lamp transfers more energy, it gets brighter. What
represents this in the model?
1 mark
Here is another circuit with two bulbs. It has the same current
as before. It has a different battery.
HHHHHHH H H
H
H
marble pusher
HH
tube
H
paddle
wheels
H H HHHHHHHHHHHH H H
H H HHHHHHHHHH
H HHHHHHHHHHHHHHHHHHH H H
H
marbles
flowing
H
MS ET
marbles
flowing
H
UG SS
H HHHHHHHHHHHHHHHHHHH H H
^ _
HHHHHHHHHHHHHHHHHHHHHHHHHHHHHH
H H H H
H H H H
HHH
In the marble model we represent the two lamps with two
paddle wheels.
c In the model, what must we do to keep the ‘current’ (your
answer to a) the same as when there is only one paddle wheel?
1 mark
d In the circuit with two lamps, more energy is being transferred
by the battery. In the marble model with two paddle wheels,
what must we do to transfer more energy?
1 mark
7 a What will happen to the fuse if the current through
this iron is too high?
1 mark
b What happens to the flow of electricity in the
circuit then?
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6
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p
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^ _
UG SS
MS ET
8 Here is a test circuit for measuring
the current through a piece of wire.
ⴙ
ⴚ
For wire A, the current is 0.2 A
and the lamp is quite bright.
ⴙ
When wire B is tested, the
current is 0.1 A and the lamp is
dimmer.
Which wire, A or B, has the
higher resistance to the
flow of electricity?
1 mark
9 a Look at the batteries in
the diagram. Which
battery stores the
most energy?
9V
X
b The lamps in this circuit work
on 1.5 V each. Write the letter
of the battery that will light
the lamps in this circuit.
1 mark
c Pippa has made the parallel circuit
shown in b above. As she added
each lamp to the circuit, she
measured the current at
point P using an ammeter.
The table shows her results.
What was the ammeter
reading when she
added the third lamp?
test
wire B
test wire A
ⴙ
1 mark
ⴚ
ⴙ
M
Electrical circuits (continued)
ⴙ
J
End of unit test
Green
1 .5 V
1.5 V
Y
Z
P
Number
of lamps
Ammeter
reading in A
1
0.48
2
0.96
3
1 mark
d Pippa then built this series
circuit. The table shows
A
her results as she added
each lamp.
i Why does the ammeter reading fall as
each lamp is added?
1 mark
ii What is the effect on the lamps as each
one is added?
1 mark
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Number
of lamps
Ammeter
reading in A
1
0.48
2
0.33
3
0.26
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Electrical circuits
J
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End of unit test
Red
1 Here are three circuits.
p
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A
ⴙ
ⴚ
ⴙ
B
ⴚ
ⴙ
ⴚ
ⴙ
ⴚ
^ _
UG SS
MS ET
C
ⴙ
ⴚ
Which circuit is shown by the
circuit diagram opposite?
1 mark
2 Here are diagrams of four circuits. Two diagrams show the same
circuit. Write the letters of these two circuits.
F
D
E
3 a What will happen to the fuse if the current
through this iron is too high?
1 mark
b What happens to the flow of electricity
in the circuit then?
1 mark
4 a What instrument is
used to measure electric
current?
1 mark
Look at the circuit diagrams.
b What is the current
measured at X?
G
8A A
A
2A
A
X
1 mark
c What is the current measured at Y?
1 mark
Y
A
A
4A
1 mark
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^ _
UG SS
MS ET
Electrical circuits (continued)
5 Here are two ways of wiring up a
circuit with two lamps.
A
B
One of the bulbs in the lamp below
has blown and needs replacing.
a Which circuit, A or B,
shows how the bulbs
are wired up?
1 mark
b Explain how you
decided this.
1 mark
6 This test circuit is for measuring the current through a lamp.
Two lamps are tested. For lamp P the current is 0.2 A. For lamp
Q the current is 0.1 A.
Which lamp, P or Q, has the higher resistance to the
flow of electricity?
A
1 mark
test
7 Anna has two torches, R and S. Each torch needs three cells to
make the lamp light. Torch R has one new cell and two older cells.
Torch S has three new cells. Anna puts a new bulb in each torch.
a Is the energy used by torch R in 10 minutes the same, more
than or less than the energy used by torch S in 10 minutes?
1 mark
b Anna replaces a second older cell in torch R. What will happen
to the current in torch R?
1 mark
c Anna is choosing a new battery for a circuit she is making with
several lamps in it. Which battery below would make the lamps
brighter?
1 mark
ⴙ
9V
T
ⴙ
J
End of unit test
Red
1.5 V
U
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marble pusher
HH
H H HHHHHHHHHHHH H H
tube
paddle
wheel
H
H
marbles
flowing
HHHHHHHHHHHHHHHHHHHHHHHHHHHHHH
H H H H
HHH
a What in the model represents the current?
1 mark
b When the lamp transfers more energy, it gets brighter. What
represents this in the model?
1 mark
Here is another circuit with two bulbs. It has the same current as
before. It has a different battery.
H
marble pusher
HH
tube
H H HHHHHHHHHHHH H H
paddle
wheels
H
H H HHHHHHHHHH
H HHHHHHHHHHHHHHHHHHH H H
H
marbles
flowing
H
MS ET
H HHHHHHHHHHHHHHHHHHH H H
UG SS
H
^ _
H
u
HHHHHHH H H
t
H H HHHHHHHHHH
?
H
p
8 Look at the circuit diagram. We can use a marble model to
represent this circuit.
H
M
Electrical circuits (continued)
HHHHHHH H H
J
End of unit test
Red
HHHHHHHHHHHHHHHHHHHHHHHHHHHHHH
H H H H
H H H H
HHH
In the marble model we represent the two lamps with two paddle
wheels.
c In the model, what must we do to keep the ‘current’ (your
answer to a) the same as when there is only one paddle wheel?
1 mark
d In the circuit with two lamps, more energy is being transferred
by the battery. In the marble model with two paddle wheels,
what must we do to transfer more energy?
1 mark
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^ _
UG SS
MS ET
End of unit test
Red
Electrical circuits (continued)
9 a If you touch something hot, the nerve cells in your fingers
detect the heat and send a message through the nerves to the
brain. How do the messages travel?
1 mark
b Peter was told by his dad not to fly his kite near overhead
electric power lines. Explain what might happen if he does.
1 mark
c Electric fences have a power supply of 12 V. They are often
walked into by animals or humans. Why are electric fences less
dangerous than overhead power lines?
1 mark
10 a Pippa has made this parallel circuit.
P
As she added each lamp to the circuit, she
measured the current at point P using an
ammeter. The table shows her results.
What was the ammeter reading when she
added the third lamp?
1 mark
Number
of lamps
Ammeter
reading in A
1
0.48
2
0.96
3
b Pippa then built this series circuit.
A
The table shows her results as she adds
each lamp.
i Why does the ammeter reading fall
as each lamp is added?
ii What is the effect on the lamps as
each one is added?
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1 mark
1 mark
Number
of lamps
Ammeter
reading in A
1
0.48
2
0.33
3
0.26
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Electrical circuits (continued)
J
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6
End of unit test
Red
...continued
p
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UG SS
MS ET
c Luigi Galvani was dissecting a frog. He touched his metal scalpel
to a nerve in the frog’s leg, and the leg kicked. Galvani guessed
that his scalpel had sent an electric pulse through the frog’s
nerve. To test this idea, he hung frogs’ legs from brass hooks
on an iron railing in his garden. The legs kicked only once,
when Galvani first touched the brass hooks to the railing.
Galvani thought the electricity came from the frog muscles,
but his friend Volta was not so sure.
Volta thought about Galvani’s experiment. He replaced the
frogs’ legs with cloth soaked in salty water. He tried the
experiment with many different metals, and found the most
electricity came when he used silver and zinc. He made a pile
from several layers of silver and zinc plates, with wet cardboard
between. He found he got a continuous flow of electricity from
this.
i
How did Volta show that the electricity did not come from
the frog muscles?
ii What was it that Volta had invented with his pile of discs?
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1 mark
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End of unit test
mark scheme
Electrical circuits
J
Green (NC Tier 2–5)
M
p
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Question
Answer
1 a
No
b
No
c
Yes
d
Yes
All correct: 2 marks; two or three correct: 1 mark;
one or none correct: 0 marks.
^ _
Mark
Level
2
2
Switch
1
3
Ammeter
1
3
c
1
3
d
1
3
UG SS
MS ET
2 a
b
3 a
Ammeter
1
4
b
2A
1
4
c
4A
1
4
Parallel circuit
1
2
B
The other bulbs are still on. In a series circuit, all the bulbs would
go out.
1
3
1
4
5
D
1
3
6 a
Marbles flowing
1
4
b
The paddle wheel turning faster
1
4
c
Turn the handle faster or harder
1
5
d
Turn the handle faster or harder
1
5
It will blow or melt.
1
4
The circuit is broken or the flow of electricity stops.
1
4
B
1
4
9 a
X
1
3
b
X
1
3
c
1.44 A
1
4
d i
ii
There is more resistance or the current is lowered by the lamps.
They get dimmer.
1
1
4
4
4 a
b i
ii
7 a
b
8
Scores in the range of:
NC Level
4–8
2
9–13
3
14–18
4
19–25
5
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Electrical circuits
J
End of unit test
mark scheme
Red (NC Tier 3–6)
M
p
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UG SS
Question
Answer
Mark
Level
1
B
1
3
2
D and G
1
3
3 a
It will blow or melt.
1
4
The circuit is broken or the flow of electricity stops.
1
4
Ammeter
1
4
b
2A
1
4
c
4A
1
4
B
1
3
The other bulbs are still on. In a series circuit like A, all the bulbs
would go out.
1
4
6
Q
1
5
7 a
Less than
1
6
b
4 a
MS ET
5 a
b
b
It increases
1
6
c
T
1
5
8 a
Marbles flowing
1
4
b
The paddle wheel turning faster
1
4
c
Turn the handle faster or harder
1
5
d
Turn the handle faster or harder
1
5
As electrical signals or electric current
1
5
If the kite touches the power line, he could get a serious electric
shock which might kill him or stop his heart.
1
5
The overhead power lines have a much higher power supply or carry
more energy or will give a more powerful electric shock.
Accept equivalent answers or suitable alternatives.
1
5
1.44 A
1
4
b i
ii
There is more resistance or the current is slowed down by the lamps.
They get dimmer.
1
1
4
4
c i
ii
He replaced frogs’ legs with cloth soaked in salty water.
A battery or cell
1
1
5
5
9 a
b
c
10 a
Scores in the range of:
NC Level
5–9
3
10–14
4
15–18
5
19–25
6
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J
M
Learning outcomes
p
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UG
Pupil check list
Electrical circuits
I can do
this very
well
I can do
this quite
well
I need to
do more
work on this
I can recognise and describe examples of
energy transfers in electrical circuits.
I can recognise and name the symbols for
all the electrical components.
I can draw circuit diagrams using the
appropriate symbols.
I can describe the difference between a
cell and a battery.
I can use ideas about how water flows in
pipes to explain how current flows around
a circuit.
I can connect and use an ammeter safely.
I can describe how current changes when
the number of cells or bulbs in a circuit
changes.
I can recognise and describe examples
of series and parallel circuits.
I can use ideas about water flow to explain
how current flows in parallel and series
circuits.
I can give one advantage of a series circuit
and a parallel circuit.
I can use my ideas of how current flows
around a circuit to predict the ammeter
readings in parallel and series circuits.
I can use a model of electricity to explain
ideas about electrical circuits.
I can describe why models are useful but
may have limitations.
I can give an example of a hazard
associated with electricity.
I can describe how to find faults in a circuit
and make it work again.
I can describe the role of a fuse in an
electrical circuit.
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Electrical circuits
J
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Glossary
Word
Definition
Energy makes things work. When anything happens,
energy is transferred.
p
?
A
t
u
ammeter
^ _
amps
UG
battery
cell
chemical energy
An object that changes chemical energy into electrical
energy.
Energy carried by electricity.
The energy a cell stores is measured in volts.
How much energy the electricity is carrying.
complete circuit
The short way of writing volts.
current
electrical energy
Stores chemical energy. More than one cell connected
together in an electrical circuit.
energy
Electricity flowing around the circuit.
fault
A device that measures the current in an electrical circuit.
filament R
Current is measured in amps.
fuse
The short way of writing amps.
model
parallel circuit
How much something slows down the electric current
passing through it. A thin wire slows down the current
more than a thick wire, so it has a higher resistance.
resistance
A circuit in which everything is in one loop.
ring main
A circuit with more than one loop.
series circuit
A very thin wire inside a light bulb, that glows when
the current passes through it. R
V
voltage
volts
An idea or picture made up by a scientist to show a
situation that cannot be seen. A model helps scientists
think through explanations.
Something that stops an electrical circuit from working.
The electrical circuit in a house. It is a parallel circuit.
A safety device for electrical circuits. The fuse has a
very thin wire which melts if the current gets too high,
and breaks the circuit.
Cells and lamps or other devices joined by wires to
make a closed loop.
Energy stored in a material, which will be given out in
a chemical reaction.
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Electrical circuits
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M
A
filament R
p
?
ammeter
fuse
t
u
amps
model
^ _ battery
parallel circuit
UG
cell
resistance
chemical energy
ring main
complete circuit
series circuit
current
V
electrical energy
voltage
energy
volts
Key words
fault
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Electrical circuits
J
A
filament R
ammeter
fuse
amps
model
battery
parallel circuit
cell
resistance
chemical energy
ring main
complete circuit
series circuit
current
V
electrical energy
voltage
energy
volts
Key words
fault
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J
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J1 Electrical energy
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UG
Electrical circuits
Green
a A cell.
b Electrical energy.
c Yes
1 Chemical energy from the cell is transferred
into the circuit as electrical energy. More than
one cell connected together makes a battery.
In a circuit, you must connect the positive end of
each cell to the negative end of the next one.
2 a three
b three
c Switches closed
Lamps lit
A, B, C
1, 2, 3
none
none
A, C
2
A, B
2
A
2
Red
a A cell.
b Battery → electrical energy → stereo →
sound energy
1 a 9V
b 9V
2 a three
b three
c Switches closed
Lamps lit
A, B, C
1, 2, 3
none
none
A, C
2
A, B
2
A
2
3 Volta invented the battery. He made the first
cell by putting two metal discs in a salt
solution. He made the battery by piling up
alternate metal discs separated by paper soaked
in salt solution.
J2 Current affairs
Green
a cell
b wires
c lamp
d in series
e amps
f Laura
g Laura
1 There is a current in the circuit. We measure
current using an ammeter. Current is
measured in amps. The current is the same
before and after a lamp.
2 The current is the same any place in the circuit.
3 By wires.
Red
a cell
b lamp
Book answers
c
d
e
1
the same
Laura
increases
Correct complete circuit with cell, lamp and
ammeter in series.
2 amps
3 a
4.00
3.00
Current
(amps) 2.00
1.00
0
0
1
2
3
Number of cells
4
b The current might be too high for the lamp
and it could burn out.
4 The model is not a good one. If a radiator
leaks, the heating would continue. But if the
lamp burns out, the circuit would stop
completely.
J3 Different circuits
Green
a A
b B
c B
d 0.1 A
e 0.4 A at P, 0.2 A at Q, 0.2 A at R.
1 resistance
2 Series circuit
Parallel circuit
The lamps are dimmer.
The lamps are brighter.
The current is the
The current is
same at all points in
shared between the
the circuit.
loops of the circuit.
3 Less current would flow in the circuit and the
lamp would be dimmer.
Red
a Longer pencil lead gave more resistance; shorter
gave less.
b 0.1 A
c 0.2 A
d parallel
e 0.1 A
f 0.4 A at P, 0.2 A at Q, 0.2 A at R
1 Resistance is how hard it is for current to flow
in a circuit. In dimmer switches, the amount of
resistance can be made to change. The more
resistance in the switch, the less current flows
and the dimmer the lamp. The less resistance,
the more current flows and the brighter the
lamp.
2 Less current would flow in the circuit and the
lamp would be dimmer.
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Book answers
J
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3 Series circuits
dimmer lamps
only one loop
less current
4 1801
Davy made
light using
electricity
i
Parallel circuits
brighter lamps
two or more loops
more current
1878/79
Swan & Edison
found thin carbon
filament which
would last
1911
1913
carbon filament
filament made
replaced by coiled
tungsten
One example could be that resistance is shown
by having a hump, mound or set of stairs in the
path that the pupils would have to climb up,
which would slow down the pupils’ rate of
movement, the current flow. Other appropriate
examples might be acceptable.
1 Individual answers with reasons.
2 Individual answers.
J5 Electrical hazards
J4 Models of electricity
Green
a
i Railway track.
ii The power station.
iii The mine.
iv Coal
b Increased
c No, the current stops flowing.
d
i Energy is represented by the matches.
ii The circuit is the white circle path along
which the pupils walk.
iii The walking pupils.
e Appropriate drawing where the matches are
green, the circle is pink, the pupils are yellow
and Mrs Fuller is blue.
1 a Jackie’s diagram does not show what happens
in the circuit. The circuit is not complete.
b Lester’s diagram shows a complete circuit
but does not show where the energy was
used.
Red
a
i Railway track.
ii The power station.
iii The mine.
iv Coal
b Increase
c Greater resistance.
d It is a good model; but it doesn’t allow for all
differences, as if the trucks should be derailed.
e The current stops flowing. No, the electricity
doesn’t spill out.
f Appropriate drawing where the matches are
green, the circle is pink, the pupils are yellow
and Mrs Fuller is blue.
g Yes, it helps as each part of an electrical circuit
has a matching piece of the model.
h An ammeter in the model could be a pupil with
a stopwatch measuring how quickly the pupils
move. The ammeter would be in the path of the
pupils.
Green
a The cells are the wrong way round.
1 More lamps can be used because the current
flowing is shared in the loops of the parallel
circuit. If one part of the parallel circuit is
broken, the other loop will continue to
work.
2
3 All plugs in appliances have fuses. If the current
in an appliance gets too high or there is a fault
in the circuit, the fuse melts, the circuit is
broken and the current stops flowing. This can
keep you from getting an electric shock. It
could also stop the wires from getting too hot
and causing a fire.
Red
1 Various faults possible such as: cells in the
wrong way round, switch broken, lamp burned
out, rusted contact with cell.
2
3 More lamps can be used because the current
flowing is shared in the loops of the parallel
circuit. If one part of the parallel circuit is
broken, the other loop will continue to work.
4 The current increases.
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