Share with Your Students
What Are Charges?
Name
Date
1. Make copies of Student Resource Page 1.1, Vocabulary,
and distribute to students. Discuss the definitions with
students as they come up throughout the section.
STUDENT RESOURCE PAGE 1.1
INFORMATION SHEET
Vocabulary
charge a property of matter
Matter can have a positive charge,
a negative charge, or no charge.
Matter has a positive charge when it
loses electrons, leaving it with more
positive than negative particles. Matter
has a negative charge when it gains
electrons, leaving it with more negative
than positive particles. Charged matter
attracts other matter that has an
opposite charge. Charged matter repels
other matter that has a like charge.
static electricity the buildup of charges
on an object
Static electricity occurs when
electrons move from one object to
another. This leaves a buildup of charges
on the surface of both objects.
Copyright ©Houghton Mifflin Company. All Rights Reserved.
electron a negatively charged particle
that surrounds the nucleus of an atom
When objects touch, one material
can give up electrons to another. When
an object gives up electrons it gains an
overall positive charge.
neutral having neither a positive or
negative charge
Atoms are usually neutral because
they have equal numbers of protons
(positively charged particles) and
electrons (negatively charged particles).
Objects that do not have a buildup of
positive or negative charges are also
neutral.
2. Draw the atom shown on the board. Use the drawing
to review atomic structure and the concept of charges.
Ask: What particles make up the nucleus? (protons and neutrons) What charges do these particles
have? (Protons have a positive charge; neutrons have
no charge.) Point out the electrons. Ask: What is an
electron? (a negatively charged particle that surrounds
the nucleus of an atom) Explain that charge is a property of matter. Discuss that materials are neutral when
they have equal numbers of positive and negative
charges.
Electron
14 • ELECTRICITY • SECTION 1 STATIC ELECTRICITY
–
Student Resource Page 1.1 (p. 14)
–
+
0 +0
+
0
Teaching Tip
Step 3: Rub balloon on dry,
clean hair with no hair products
such as spray or gel.
Proton
–
Neutron
A Model of an atom
Safety
Step 3: Use caution rubbing a
balloon on student hair due to the
possibility of spreading parasites
such as lice.
4 • EXPERIENCE SCIENCE
3. To get students thinking about static electricity, inflate
a balloon and rub it against your hair. Then hold the
balloon a few centimeters from your head and have
students note how your hair stands on end. Ask: What
is static electricity? (a buildup of charges on a
material)
Name
4.Display the transparency Static Electricity. Use it to
explain that when materials touch, electrons can move
from one object to the other. Discuss the top drawing.
Ask: What causes the comb to have a negative
charge? (Electrons move to the comb, so the comb has
more negative than positive charges.) Why does the
cloth become positively charged? (It loses electrons
and has more positive than negative charges.)
Date
STUDENT RESOURCE PAGE 1.2
INFORMATION SHEET
Static Electricity
Negatively charged comb
–– – –– –– ––
+ + +
+ +
+ + +
+ + +
– –
–– – – –
+ +
+ +
+
+ +
+
Positively charged wool
Copyright ©Houghton Mifflin Company. All Rights Reserved.
When a wool cloth is rubbed on a plastic comb, the cloth loses
electrons and the comb gains them. The comb now has a
negative charge and the wool has a positive charge.
– – – – – – – –
– – –
+ + + + +
+ + + + +
+ + + + +
+
+
+ +
5. Tell students that charges exert forces (pushes or pulls)
on other charges. Explain that unlike charges attract,
or pull toward each other. Like charges repel, or push
away, each other.
+ +
+ +
+
+ + +–
– –
6. Have students look at the bottom drawing. Explain
that the comb has a negative charge and the paper is
neutral. Ask: How does the drawing show that like
charges repel? (The electrons at the surface of the
paper are pushed away from the paper’s surface by the
negative charges on the comb.) What effect does this
have on the paper? (The surface of the paper is left
with a positive charge.)
Paper
When a negatively charged comb is brought near a neutral piece
of paper, the electrons on the surface of the paper are repelled,
or pushed away. This leaves the surface of the paper with a
positive charge.
ELECTRICITY • SECTION 1 STATIC ELECTRICITY • 15
Student Resource Page 1.2 (p. 15)
Name
Making Static Electricity
Making Static
Electricity
Date
STUDENT RESOURCE PAGE 1.3
ACTIVITY SHEET
1 What happens when the neutral comb is held near the tissue
10 minutes
pieces?
Pairs
Nothing happens.
Objectives
• Students recognize that static electricity is the buildup of charges
on an object.
2 What happens when the comb rubbed with wool is held
near the tissue pieces?
The tissue is attracted to the comb.
• Students observe that electrically charged objects exert forces of
attraction and repulsion on each other.
3 What happens when the comb rubbed with paper towel is
held near the tissue pieces?
4 What did you observe about materials with opposite
charges?
They attract each other.
Copyright ©Houghton Mifflin Company. All Rights Reserved.
The tissue is attracted to the comb.
Materials
For each pair
Student Resource Pages
• 1.3 Making Static Electricity
1
Inquiry Focus
• Infer
comb, plastic
1 pc. *facial tissue
1
1 pc.
*paper towel
wool cloth
*Not provided in kit
16 • ELECTRICITY • SECTION 1 STATIC ELECTRICITY
Student Resource Page 1.3 (p. 16)
SECTION 1 STATIC ELECTRICITY • 5
Making Static Electricity (continued)
Teaching Tip
Step 1: Static electricity experiments only work on dry days.
1. Distribute the Resource Page and materials.
Make copies and distribute Student Resource Page
1.3, Making Static Electricity, to students. Distribute
materials to each pair.
2. Students observe that neutral objects don’t
interact.
Have students tear the tissue into six tiny pieces
and place the pieces on a desk. Tell students that the
tissue and the comb are both neutral (have no electrical
charge). Tell them to hold the comb near the tissue.
Have them observe what happens and record their
observations on the Resource Page. (Nothing happens.)
3. Students charge the comb and observe its
effect on the tissue.
Have students rub the comb 10 times with the wool
cloth. Tell them to hold the comb near the tissue pieces
and observe what happens. (The tissue pieces are
attracted to the comb.) Ask: What can you infer
about the charges on the comb and the tissue?
Explain. (They are opposite, because opposite
charges attract.)
A Creating a static charge on the comb
4.Students charge the comb using a different
material.
Tell students to rub the comb 10 times with the paper
towel. Have them hold the comb near the tissue pieces
and observe. (The tissue pieces are attracted to the
comb, but not as much as with the wool.) Ask: Which
charges the comb more—the paper towel or the
wool? (the wool)
5. Analyze the results.
Discuss with students why rubbing the comb with the
wool causes the tissue to be attracted to the comb. Explain
that when the comb is rubbed with the wool, the wool
loses electrons and the comb gains them, giving the
comb a negative charge. When the negatively charged
comb is brought near the neutral tissue, the electrons on
the surface of the tissue are repelled, giving the tissue a
positive charge. The negative charge of the comb then
attracts the positive charge of the tissue.
Assessment
Ask: If rubbing a comb with wool causes the
comb to gain electrons, what is the overall charge
on the comb? (negative) On the wool? (positive)
6 • EXPERIENCE SCIENCE