Turn It On!–BC Teacher's Guide
3
Lesson
E
lectricity?
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Student Book pages 10–11
In this lesson: Students explore the nature of
electricity and experiment with static electricity.
Specific Outcomes
• evaluate various methods for producing
electrical charges (T1)
• communicate their observations, experiences,
and thinking in a variety of ways (P3)
• manipulate and control a number of variables
in an experiment (P14)
• work cooperatively with others (A1)
• show scientific interest and curiosity (A2)
• show increasing confidence as scientific
problem solvers (A9)
Assessment
• Consider how well students can explain
where the buildup of excess electrons must be
to cause the attractive forces. (Excess electrons
on an object move or pull things, showing the
observer which attractive force is present—
negatively and positively charged materials attract
one another, and materials of the same charge
repel one another.) (T1, P1, P5)
• After the Exploration, ask students to write
descriptions and make drawings to show
what happened to the balloons after they
were rubbed with wool. Observe whether
students use the correct terms and know
when they have “charged” things or
produced an “attractive force.” (T1, P3)
Getting Organized
Time Required: Activate 10-15
min; Explore 15-20 min; Apply
20-25 min
Advance Preparation: Gather
materials.
Lesson Vocabulary
static electricity: a form of electricity resulting
from the accumulations of imbalanced charges
on the surface of objects
charge: a quality of electricity that can be
either positive or negative; similar charges repel
each other and opposite charges attract each
other
positive: in a charge, produced by the lack of
electrons
negative: in a charge, produced by an excess of
electrons
electrons: negatively charged particles
atoms: the smallest particle of an element that
has the properties of the element
electric discharge: the rapid movement of
electrons away from a charged object
Lightning strikes in the atmosphere,
which might be occurring hundreds of
kilometres away, cause most of the
static you hear on your AM radio.
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Lesson 3:What Is Electricity?
Turn It On!–BC Teacher's Guide
Content Background
E
lectricity is the work of subatomic
particles called electrons.
Everything around us, including our
bodies, contains these particles, so
everything can be thought of as being
partly electric. Electricity can be seen
in nature as lightning, as aurorae, and
in electric eels.
In static electricity, an electric
charge collects on the surface of an
object due to the loss or gain of
electrons. The buildup of the charge is
the result of the redistribution of
charges in the object. In current
electricity, the electrons move through
objects or substances. We can easily
produce static electricity by picking up
particles from the surface of one
object and depositing them
somewhere else—as when you rub
particles off a carpet with your shoes
and deposit them on a receptive
doorknob with your hands.
Thanks largely to the pioneering
work of seventeenth-century French
scientist Charles du Fay, we know that
there are two charges, and that similar
charges repel, and opposite ones
attract. Benjamin Franklin invented
the idea of an electric charge, labelling
an excess of electric charge as positive
(+) and a deficiency as negative (–).
Franklin’s experiments led him to
believe that lightning is a giant spark
of static electricity, and thunder is a
huge crackle of static charge. In 1752,
in Philadelphia, Franklin proved his
hypothesis—he succeeded in capturing
some electricity to use in his
experiments by flying a kite before a
lightning storm. A wire attached to
the top of his kite attracted a negative
charge from a storm cloud. Electric
current travelled down the wet kite
string toward a metal key and
ultimately to a Lewden jar designed to
store electric energy. Franklin was
lucky to survive his experiment—
others who have tried the experiment
have been killed by the lightning.
Lightening is a spectacular example of
electric discharge.
Lightning is the electrostatic spark
that results from the rapid movement
of charged particles within a
thundercloud or between the cloud
and the ground, the air, or another
cloud. There are numerous types of
lightning. The most common type is
intracloud lightning, in which internal
charges form a spark. When the flow
of charges is between the cloud and
Earth, the result is cloud-to-ground
lightning (what most people see) or
ground-to-cloud lightning, depending
on the direction in which the charges
flow.
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Lesson 3:What Is Electricity?
Turn It On!–BC Teacher's Guide
Activate
Explore
Have You Seen Electricity?
Preparing for the Exploration
Ask students:
Suggested Grouping: pairs
Have you ever seen any evidence of
electricity? (Students may report having seen
blue sparks of static electricity, an electric current
escaping from a damaged appliance, and lightning
bolts. Some students may have seen
demonstrations of high-voltage electric currents
in a science museum.)
Invite students to describe how these different
electric currents are similar in shape, sound,
and colour, but have different intensities.
Introducing Static Electricity
Have students read the introductory paragraph.
Encourage them to recall any instances when
they received shocks of static electricity.
What was similar about these situations?
What do you think caused the shock?
Write their responses on the board or chart
paper to return to later when writing the
characteristics of static electricity.
Some students may think that electricity is
limited to batteries and wall sockets. You may
wish to do a brief demonstration with a fluorescent lighting tube and some plastic wrap. Darken
the room and rub a section of the tube vigorously with the plastic wrap. It will glow where
it was rubbed. Ask students to predict why the
tube began to glow and what this demonstration
has in common with electric shocks that come
from rubbing stocking feet on a carpet.
P re c o nc ep
ti ons
Students m
ay not unde
rstand how
a shock from
a doorknob h
appens.
This lesson w
ill help them
understand how s
tatic charge
s build up.
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Lesson 3:What Is Electricity?
Approximate Time: 15-20 min
Materials per Group: balloons, wool, plastic
wrap, silk, paper, felt, goggles, pens/pencils,
Science Journals
(Student Book page 10)
Make static electricity.
1. Make sure students are wearing goggles
when they start this experiment.
2. Ask what they think makes the balloons
stick to the walls and each other. Explain to
students that an electric charge on the
balloon, called a static charge, makes the
balloons stick to the wall and to each other.
3. When the balloons are rubbed with wool,
they will repel one another.
4. Discuss the idea of fair test with the
students. Remind them that they should
only change one variable in an experiment
at a time. Ask them to choose several
different materials, write out their steps to
compare the materials, and show it to you
before they start. Students can record their
results in a chart.
Troubleshooting
For best results, conduct this experiment on a cool,
dry day, preferably in the winter.
Exploration Results
The balloons rubbed with silk, plastic wrap,
felt, and paper also produce static electricity.
Turn It On!–BC Teacher's Guide
Apply
Interpret your results.
Exploration Connection
(Student Book page 10)
(Student Book page 11)
• The balloons stuck to the wall for a few
minutes. Students observe that rubbing the
balloons more vigorously will increase the
length of time they cling to the wall.
• The balloons repelled one another. The
longer students rub the balloons, the more
they repel one another.
• The balloons attract one another and stick to
each other for a short time.
• Static charges can either attract or repel each
other.
Charged on static electricity
Communicate your results.
• Ask students to share their thoughts about
how their balloons reacted on a chart and
compare their charts. The differences in
results come about because of different
variables in the experiment: for example,
how much they rubbed the balloons and for
how long.
Ask students to read the text on page 11 of the
Student Book and answer the questions at the
end. Students will realize that because the
balloon and the wall were attracted to each
other, they had different charges.
The green balloon moves forward and
makes contact with the orange balloon. Some
of its negative charge then moves to the orange
balloon. At that point, the two negatively
charged balloons would repel each other.
Students will find that when they rub their
hands over a static balloon, electrons are being
removed and the balloon loses its electric charge.
Make an Electroscope
You or a group of students could make an
electroscope for students to use in testing
whether materials are charged (see
Reproducible 3A: Make an Electroscope).
Students can first touch the foil the foil ball
with items that have not been charged and
observe the results (nothing happens). Then
students can charge items such as pens or glass
rods, by rubbing them on silk or wool. Have
students explain answers when items they have
charged are placed near the end of the foil ball:
- Where did the excess electron charges go?
- What happens to the strips of foil?
- Why do the foil strips move apart? (An object
is given a positive charge by rubbing on silk or wool.
When the positively-charged object is held near the
foil ball, negative charges are drawn up the wire to
the ball, and only positive charges are left on the
folded foil strip. Since like charges repel one
another, the foil pieces move apart.)
23
Lesson 3:What Is Electricity?
Turn It On!–BC Teacher's Guide
Apply
Struggling/ESL Students
Ask:
What happens if you touch the foil ball?
Have students rub stocking feet on a rug to
create a static charge on their bodies and then
touch the foil ball again. Ask students to
explain (orally or in a labelled diagram) the
path the electrons took from the rug to their
stocking feet, along their bodies, to their
hands, and onto the ball.
Ask students to look up the definitions for
static and static electricity in a dictionary.
Knowing that static means “not moving” may
help them understand that static charges are at
rest on the surfaces of objects. Encourage them
to look for other words with stat as their root
(e.g., stationary, statue).
Characteristics of Static Electricity
With the students, make a list of the characteristics of static electricity. (It is caused by positive
and negative charges on an object.These charges
attract or repel other objects with negative and
positive charges.) Keep this list to compare with
the characteristics of current electricity in
Lesson 4.
Your dry clothes stick together because static
charges can build up on the fabric when the
garments rub together as you move.
Global Perspectives
The discoveries that led to the use of electricity
as an energy source started with the study of
static charges. German scientist Otto von
Guericke laid the groundwork for modern
electric experimentation by devising a machine
to produce static electricity. His machine, built
in 1660, was essentially a sulphur ball turned
by a hand crank. When von Guericke rubbed
his hand on the revolving ball, he produced
static charges. After careful experimentation,
he noticed that static charges can repel as well
as attract. He originated the concept of
transmitting electricity when he sent a static
charge down a few feet of thread to attract
fluff. His electrostatic generator also produced
noisy sparks of light, inspiring further studies
about the nature of electricity.
24
Lesson 3:What Is Electricity?
Turn It On!–BC Teacher's Guide
Extending Learning
Electric Comb
Have students complete Reproducible 3B:
Charged Comb. Discuss their results, including
which part they find is rubbing on or off
electrons for an attractive force, and whether
changing the material changes the type of
attractive force.
Lightning
Ask students to investigate lightning. When
and how does it occur? How can you tell how
far away it is? What safety rules should
everyone follow when there is lightning?
Brainstorm a list of questions about lightning
and students pick one to find the answer to
share with others.
Preventing Static Charges
Bring to class two fabric softener sheets (“dryer
cloths” marketed to reduce static electricity in
a clothes dryer). One of the sheets should be
used, the other new. Students can examine the
cloths and predict how a cloth might work to
reduce static electricity. (The dryer’s heat releases
a chemical from the sheet that forms a coating on
clothes so electrons are not so easily rubbed off the
clothes.)
Have students investigate techniques for
preventing static charges (for example,
grounding, and raising humidity to reduce
static charges). They can present their findings
in the form of labelled diagrams.
Charged Water
Students can learn more about static charge by
observing how a static charge deflects a stream
of water.
Materials: balloon, sink with running water
1. Blow up a balloon and tie it closed.
2. Unplug the sink and run a very thin stream
of water from the tap.
3. Rub the balloon on your clothing. Without
getting the balloon wet, hold it near the
stream of water. What happens to the
water? (Students will observe that the stream
of water moves toward the electrically charged
balloon.This means that the side of the stream
nearest the balloon carries a charge opposite to
the balloon.)
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Lesson 3:What Is Electricity?
Turn It On!–BC Teacher's Guide
3A
Name __________________________________________ Date
Make an Electroscope
1. If the wire is covered in insulation, remove the covering
from about 5 cm at each end. Push the wire through the
covering for the jar. (If you’re using a cork or rubber
stopper, make a hole through the centre of the stopper
using the nail. If you’re using a cardboard disc, make a
small hole in the middle of the disc using the scissors
and tape the wire in place.)
2. Check that about 10 cm of the wire is showing through
the top, and about 20 cm through the bottom of the
covering. Bend the lower end of the wire at right angles
to make a flat hook.
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foil ball
3. Fold the foil strip in half and hang
it over the wire hook. (Check that
there is no insulation between the
foil and the wire.)
4. Cover the bottle tightly with the
stopper or disc. Use tape if
necessary to hold it in place. Make
sure the foil stays on the wire.
5. Crumple the foil into a ball, and
press it around the top of the wire.
gumwrapper foil
6. Test charges by holding an object
next to the foil ball. Observe what
happens to the foil strip.
26
Lesson 3:What Is Electricity?
Copyright © 2005 Scholastic Canada Ltd.This page may be reproduced for classroom use by the purchasing school.
Turn It On!–BC Teacher's Guide
Name __________________________________________ Date _____________________________________
3B
Charged Comb
How can a comb be used to demonstrate static electricity? Design
an experiment in which you rub a comb on a piece of wool and
then test to determine if there is an attraction to a variety of
materials (such as bits of paper, feathers, hair, and so on). Use this
page to help you plan your experiment and record your results.
1. What is the question you would like to answer?
2. What is your hypothesis? (You can record several hypotheses,
and then choose the one you think is best.)
3. Which materials will you test?
4. Which variables will you control?
5. Which variable will you change?
6. Record your observations.
7. What do you conclude based on your observations?
8. Was your hypothesis supported? Give reasons why or why not.
27
Lesson 3:What Is Electricity?
Copyright © 2005 Scholastic Canada Ltd.This page may be reproduced for classroom use by the purchasing school.