Living Science (Second Edition) Unit Test 2
8ʳ Making use of electricity
S2 Science Test
Unit 8ġ Making use of electricity
Name:____________________________
ΰʳ ʳ ʳ α
Time and Marks
Class: ____________________________
Part A: 35 min / 100 marks
Date: ____________________________
Parts A & B: 45 min / 120 marks
Note:
ʳ
1
Attempt ALL questions.
2
Write your answers in the spaces provided on the Answer Sheets.
ʳ
Part A (Level 1)
A
True or false questions (5 marks, 1 mark each)
Study each of the following statements. Write ‘T’ for a true statement and ‘F’ for a false statement on the answer
sheets.
1
Electric cells store electrical energy.
2
A bulb in a circuit will light up once it is connected to one end of a battery.
3
When the resistance of a circuit increases, the current flows around the circuit will become smaller.
4
Two fuses rated 15 A connected in series allow a current larger than 30 A to flow through them.
5
The live wire in a plug is blue in colour.
Multiple-choice questions (20 marks, 2 marks each)ġ
B
Choose the correct answer for each of the following questions.
1
Which of the following circuits has the bulb lighted up when the circuit is closed?
A
2
B
C
Which of the following is an electrical conductor?
A
Rubber
B
Wool thread
C
Iron nail
D
Wooden board
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D
Living Science (Second Edition) Unit Test 2
3
4
Which of the following copper wires has the smallest resistance?
A
Short and thick
B
Short and thin
C
Long and thick
D
Long and thin
ʳ
Which of the following electric components has to be used in a dimmer switch or a volume controller?
A
5
B
C
D
C
D
Which of the following is a parallel circuit?
A
6
8ʳ Making use of electricity
B
In general, the electrical components in a circuit have certain resistance. When an electric current flows
through them, part of the electrical energy is lost in the form of
7
A
chemical energy.
B
potential energy.
C
heat energy.
D
sound energy.
Which of the following statements about the fuse are correct?
(1)
It is made up of alloy with low melting point.
(2)
If the current exceeds the fuse rating, the fuse blows and cuts off the electricity supply.
(3)
All kinds of fuse have the same fuse ratings.
A
(1) and (2) only
B
(1) and (3) only
C
(2) and (3) only
D
(1), (2) and (3)
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Living Science (Second Edition) Unit Test 2
8
9
8ʳ Making use of electricity
What are the colours of the neutral and earth wires in a plug respectively?
A
Brown; blue
B
Blue; Black
C
Black; yellow and green
D
Red; yellow and green
An electric iron has a power rating of 1500 W. If it has been switched on for half an hour, how much energy
has been consumed?
10
A
0.5 kW h
B
0.75 kW h
C
1.25 kW h
D
1.5 kW h
Which of the following electrical appliances make use of the magnetic effect of a current?
(1)
Electric iron
(2)
Hair dryer
(3)
Fire alarm
(4)
Loudspeaker
A
(1) and (3) only
C
(1), (2) and (3) only
B
(3) and (4) only
D
(1), (2), (3) and (4)
Fill in the blanks (20 marks, 2 marks each)ġ
C
Complete the following sentences.
1
Current can only flow in a
2
Copper allows electricity to flow through. Thus, it is a
through. Thus, it is an
c .
3
An increase in the voltage in a circuit will
4
A
e
circuit.
5
, each of the live wire and neutral wire branch into two parts that current can flow through the
In a
f
two paths to each socket.
6
There are two ratings marked on an electrical appliance. They are
7
The
8
A
circuit.
d
b
; Wood does not allow electricity to flow
the electric current flowing through the circuit.
is an electric component having a certain resistance that can decide the size of current in a
i
j
a
g
rating and
h
rating.
of an appliance is the rate at which electrical energy is transferred to an appliance in a second.
can be produced by a magnet on a wire carrying an electric current.
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Living Science (Second Edition) Unit Test 2
Questions (55 marks)ġ
D
1
8ʳ Making use of electricity
Figure A shows a simple circuit and figure B shows a water flow model.
water pump
water
water pipe
fan
A
a
In figure A, draw ‘
B
’ and ‘
’ to illustrate the directions of the flows of current and
electrons respectively.
b
(4 marks)
If we want to measure the current flowing through the circuit in figure A, what electric
component should be used? Draw a circuit diagram for the whole set-up.
c
(6 marks)
Compare figure A and figure B. State the features in figure B that represent the following
in figure A.
2
i
Connecting wire
(1 mark)
ii
Light bulb
(1 mark)
iii
Electric current
(1 mark)
iv
Electron
(1 mark)
v
Battery
(1 mark)
The figure below shows a circuit connected with a battery, connecting wires, a bulb, a switch and a rheostat.
+
- + -
A
B
a
Draw a circuit diagram for the above set-up.
(5 marks)
b
What is the major difference between a resistor and a rheostat?
(3 marks)
c
i
What happens if we slide the contact of the rheostat from one side to another?
(2 marks)
ii
Explain your answer in c i.
(4 marks)
d
If we want to increase the brightness of the bulb in the circuit, should we slide the contact
of the rheostat towards A or B?
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(2 marks)
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Living Science (Second Edition) Unit Test 2
3
8ʳ Making use of electricity
The figure below shows a ring circuit.
ring circuit
a
Write one advantage of using a ring circuit.
(1 mark)
b
What do ‘E’, ‘N’ and ‘L’ represent in the figure?
(3 marks)
c
Write down the use of ‘E’ in the figure.
(2 marks)
d
Due to safety, fuses with ratings 5 A, 15 A and 30 A are installed inside the consumer unit.
e
4
From the diagram, which electrical appliance has the greatest electrical power? Why?
(3 marks)
In the lighting circuit, are the bulbs connected in series or in parallel? Explain briefly.
(3 marks)
The table below shows the consumption of electricity of some household electrical appliances.
Complete the following table and show your working steps.
Electrical appliance
f
Electrical energy consumed
(kW h)
Electrical power rating
Time in use
Leon light
50 W
1 week
a
(2 marks)
Television
100 W
4 hours
b
(2 marks)
Water heater
1500 W
30 minutes
c
(2 marks)
Electric fan
200 W
2 hours
d
(2 marks)
Microwave oven
1000 W
45 seconds
e
(2 marks)
If one unit of electricity costs $0.9, calculate the total cost of electricity for the consumption. (2 marks)
Ё End of Part A Ё
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Living Science (Second Edition) Unit Test 2
8ʳ Making use of electricity
Part B (Level 2) (20 marks)
Power Failure in Hot Summer
Read the news article about power failure below and answer the questions.
Several incidents of power failure happened in the estates of Kwai Chung and Tai Po in the past few days.
Daily lives of the residents were seriously affected.
The power supply company found that the damaged electric wires have been used for more than 30
years. Ageing of the estates is the main reason for the incidents. Moreover, frequent lightnings in the past
few days caused damage to the overhead cables which also accounts for the power failure.
The affected residents said that they could not sleep well because they could not turn on the
air-conditioners or electric fans. Due to the hot weather, some residents moved to their relatives’ homes,
the public shelter or the hotels. Some residents even went to the shopping mall or restaurants nearby in
order to stay away from the hot air.
1
According to the news above, list two causes of power supply failure in the housing estates of
Kwai Chung and Tai Po recently.
(4 marks)
2
Why does power supply failure usually happen in summer? List two reasons.
(4 marks)
3
If you were one of the affected residents, give two suggestions to prevent the incident from
happening again.
4
(6 marks)
What can the power supply company do to prevent power supply failure from happening again?
Give two suggestions.
(6 marks)
Ё End of Part B Ё
© Oxford University Press 2005
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Living Science (Second Edition) Unit Test 2
8ʳ Making use of electricity
S2 Science Test
Unit 8ġ Making use of electricity
Answer Sheets
Name: ____________________
ΰʳ ʳ ʳ ʳ α
Class: ____________
Marks: __________________
Total: 100% (Part A) / 120% (Parts A & B)
Section A Total
Do not write in
this box
Part A (Level 1)
A
True or false questions (5 marks, 1 mark each)
1 __________
B
2 __________
3 __________
4 __________
5 __________
Multiple-choice questions (20 marks, 2 marks each)
Section B Total
Do not write in
this box
1 __________
2 __________
3 __________
4 __________
6 __________
7 __________
8 __________
9 __________ 10 __________
C
5 __________
Fill in the blanks (20 marks, 2 marks each)
a ______________________
b ______________________
c ______________________
d ______________________
e ______________________
f ______________________
g ______________________
h ______________________
i ______________________
Section C Total
Do not write in
this box
j ______________________
D
Questions (55 marks)
b __________________________ should be used.
1 a
c i
_____________ ii _____________ iii
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_____________ iv _____________
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v _____________
Living Science (Second Edition) Unit Test 2
8ʳ Making use of electricity
2
b _________________________________________________
a
_________________________________________________
c i
______________________________________________
ii ______________________________________________
______________________________________________
d _________________________________________________
3 a ___________________________________________________________________________
b ___________________________________________________________________________
c ___________________________________________________________________________
___________________________________________________________________________
d ___________________________________________________________________________
e ___________________________________________________________________________
4 a ___________________________________________________________________________
b ___________________________________________________________________________
c ___________________________________________________________________________
d ___________________________________________________________________________
Section D Total
Do not write in
this box
e ___________________________________________________________________________
f
___________________________________________________________________________
Part B (Level 2) (20 marks)
1 _______________________________________________________________________________
2 _______________________________________________________________________________
_______________________________________________________________________________
3 _______________________________________________________________________________
_______________________________________________________________________________
4 _______________________________________________________________________________
_______________________________________________________________________________
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Part B Total
Do not write in
this box
Living Science (Second Edition) Unit Test 2
8ʳ Making use of electricity
S2 Science Test (Unit 8 Making use of electricity)
Answers
Part A (Level 1)
True or false questions (5%)
A
1F
2F
3T
4F
5F
1 m each
Multiple-choice questions (20%)
B
1B
2C
3A
4D
5D
6C
7A
8C
9B
10 B
2 m each
Fill in the blanks (20%)
C
a closed
b conductor
c insulator
f ring circuit
g voltage / electrical power
d increase
e resistor
h electrical power / voltage
i electrical power
j force
2 m each
Questionsġ(55%)
E
1 a
2 m each
Ammeter should be used.
b
1m
battery: 1 m
connecting wire: 1 m
A
light bulb: 1 m
ammeter: 1 m
closed circuit: 1 m
c i
water pipe
1m
ii fan
1m
iii stream of flowing water
1m
iv water particles
1m
v water pump
1m
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Living Science (Second Edition) Unit Test 2
8ʳ Making use of electricity
2 a
1 m for each electric component
b The resistance of a resistor is fixed whereas the resistance of a rheostat can be changed.
c i
3m
The bulb becomes brighter or dimmer gradually.
2m
ii The resistance of the rheostat can be changed by moving the contact. Lower (Higher) resistance
allows larger (smaller) current to pass through and the bulb becomes brighter (dimmer).
4m
d Towards A.
2m
3 a This is a cheaper way for setting up a household circuit.
b E: earth wire; N: neutral wire; L: live wire
1m
1 m each
c E (i.e. the earth wire) connects the metal case of an appliance to the earth. It can protect us from electric
shock even the live wire is damaged.
2m
d Oven.
1m
Because it is connected to a fuse with the greatest fuse rating and allows the greatest current to
flow through. Its electrical power is thus the greatest.
2m
e They are connected in parallel.
1m
If one of the bulbs fails, the others can still light up.
2m
4 a (50/1000) x 7 x 24 = 8.4
2m
b (100/1000) x 4 = 0.4
2m
c (1500/1000) x (30/60) = 0.75
2m
d (200/1000) x 2 = 0.4
2m
e (1000/1000) x (0.75/60) = 0.0125
2m
f
(8.4+0.4+0.75+0.4+0.0125) x 0.9 = $9
2m
Part B (Level 2) (20%)
1 The electric wires used in the housing estates became old and were damaged by overloading;
The overhead cable was damaged by lightning.
2 m each
2 Residents use more electrical appliances such as air-conditioners and electric fans in summer.
Increased consumption of electricity leads to overloading; Lightning occurs more frequently in summer.
The overhead cable will be damaged at higher chance.
2 m each
3 Check the power supply system in the building. / Replace damaged or old electric wires. /
Reduce the consumption of electricity. (Any 2 or other reasonable answers)
3 m each
4 Install power supply back-up;
Install a lightning rod to reduce the effect of lightning. (or other reasonable answers)
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3 m each