- University of Virginia
- Physics Department
Introduction to Static Electricity
A Physical Science Activity
2003 Virginia SOLs
- learn the difference between charged and uncharged objects and how they
- learn that like charges repel each other and opposite charges attract each
- understand the concept of polarization of charge as a means of attraction;
- explore how positive and negative charges are created.
Motivation for Learning
Demonstration: the kissing balloon
- Length of thread (2 m)
- Permanent marking pen
- Wool cloth, piece of silk, or fake fur
- Words to the story
- (while students are out of the room)
- Inflate the balloon and draw a face on the balloon using a marker.
- Hang the balloon from the ceiling with thread so that the face is right
side up and the balloon is the height of your head.
- Rub the nose of the balloon with a wool cloth, but nowhere else on the
balloon. If properly charged, the balloon will now turn and face you when
you are reasonably near ( 40 cm ). If you walk around the balloon, the face
should rotate to follow you. If your head gets closer ( less than 20 cm ),
the balloon should be attracted to you and "kiss" your face.
- You are now ready for your students to return to the classroom. Do not
allow them to go near the balloon.
(while students are in the room)
Tell the students this story: "Students, I'd like you to meet a friend of mine.
His name is George. George, meet the smartest eighth grade in the state." (At
this point you are at least 2 meters away from George).
"There are a couple of things I think you should know about George. First, he's
nearsighted; does anyone know what that means? He can't see very well far away.
Second, he has an awful crush on me. He likes me so much that he just can't
keep his eyes off me- when he can see me that is." (Walk over to George and
he will turn to face you)
"You see? He just stares at me, and keeps staring at me as long as I'm close
enough for him to see me." (Walk away.) When I walk away, he just looks all
over, trying to find me again." (Move closer again) "You'll be able to tell
when I'm in his range of vision because he'll look right at me." (Walk around
George and his face will follow.) "See, I told you he likes me. Now, if you
promise not to tell anyone, I'll let George kiss me - just once, and the cheek."
(Lean over, where your cheek is very near George. He will kiss you) "Aw, that's
"Now, for the next few days, we're going to do a few things that should give
you some clues about George. We'll visit him again another day." (You can adapt
the story however you feel beneficial; George could be Sue, or a faithful old
dog. One of the important things is relating eyesight range to electric field
(Adapted from Hands on Physical Activities by Marvin Tolman, Activity
Everything around us is normally neutral in charge. Water, wood, walls, desks,
people, almost everything. We did something to George to make him charged, so
he acted funny. But regular objects like desks, pens and pencils are not normally
charged. Show students the model of how like charges repel and opposites attract,
and if something is charged, it attracts a neutral one by attracting the opposite
charges in that neutral object. This is called polarization (it is discussed
in the answers to the questions). Tell the students that today they will see
how charged objects interact with all these regular objects and how charged
objects act with each other. How does something become charged? The simplest
way is to rub the charges off. We will be charging balloons today by rubbing
one part of them with wool. Does the whole balloon become charged or only where
it is rubbed? It is just where you rub. We will put a dot on the balloon so
we remember where it was rubbed. We can rub it with a lot of things to make
it charged, for example hair is good at charging objects. But it messes up your
hair if you rub things on your head. This is why we use a piece of wool, which
is actually sheep's hair.
To print out the Student Copy only, click
Student Activity #1 - Can neutral objects attract non-neutral ones?
- 1 balloon
- Small pieces of paper, pieces of sugarless puffed cereal
- Water faucet
- Wall: concrete, metal, plastic
- Wool cloth or a piece of silk
- Blow up the balloon and tie off the end. Put a mark on one side of the
balloon. This dot lets you know which area you rubbed.
- Rub the balloon with the wool at the dot.
- Put the non-charged (away from the dot) part of the balloon near the pieces
of paper and the cereal. Observe what happens.
- Put the charged (near the dot) part of the balloon near the pieces of paper
and cereal. Observe what happens. If nothing happens in this case, vary the
distance between the balloon and cereal.
- Rub the dot again and try to stick the balloon on different walls on the
charged and non-charged parts of the balloon: Concrete, glass, metal, plastic.
Observe what happens.
- Put the un-charged and charged part of the balloon near a small water stream
from the faucet. Observe what happens.
- What happened when you put the balloon
near the cereal and paper? Was it any different for the side of the balloon
with the dot?
- Could you get the balloon to stick on all of the different types of walls?
How about the part of the balloon not near the dot?
- Did the balloon attract the water near the dot? Away from the dot?
- From these experiments, what can you say about how charged objects affect
regular neutral objects like paper, walls, and water?
- Why did we pick less heavy things like paper and cereal in our test rather
than something heavy like a pen or a pencil?
- After all of your observations, do you know now whether charged objects
can attract neutral objects?
Answers to Questions:
- The balloon will attract the cereal at the place that it has been rubbed.
Away from the dot, there will be no attraction of the cereal. This is because
the charging of the balloon is local; the charge doesn't spread all over the
balloon if it is just rubbed in one place. The balloon is an insulator.
- The balloon will stick to all types of walls as well. The reason for this
is that the neutral object is polarizing. When the charged object gets near
the uncharged one, it attracts all of the opposite charges closer to the charged
- The balloon will also attract the water for similar reasons to #2. It works
much better when the charged area of the balloon is near the water stream.
- The attraction occurs when the charged balloon goes near the faucet, the
wall or the cereal for the same reasons explained in #2.
- We picked light materials such as the cereal so that we could see the movement
due to the polarization. If the objects were too heavy, there would not be
enough electrical attraction to overcome the gravitational force.
- Yes, by taking advantage of the polarizing effect, charged objects can
attract neutral objects by moving the charge around on the neutral objects.
The unlike charges are then closer than the like charges, and the result is
that the attraction is greater than the repulsion. The electrical force goes
as q1q2/r2, where the q are charges and r is the distance between the charges.
Student Activity #2 - The Balloon Electroscope
- 2 identical balloons
- Wool cloth, silk cloth, or piece of fake fur
- Water sprayer per 2 groups
- Blow-up the balloons, tie the ends in a knot, and tie thread to the ends
of each balloon.
- Tie the balloons together using the thread so the balloons are about 80
- Have one person hold the uncharged balloons by the thread and move the
balloons together. Record observation.
- Rub each balloon all over with the wool as best as possible. Move one balloon
near the other but do not allow them to touch. How do they react with each
other? Record observations.
- While the balloons are repelling each other, have the students gently mist
the balloons with water.
- Why did the balloons repel each other after they were rubbed all over with
- What would have happened if we rubbed one side of the balloons instead
of all over?
- Why did the balloons fall back towards each other after they were sprayed
- What effect does damp weather have on electrical charges?
- During which time of the year would it be best to do experiments using
Answers to questions
- After rubbing the balloons with the wool, the balloons have the same charge
and will repel each other.
- The side of the balloon that was rubbed has been charged and wants to be
as far away as possible from the other charged balloon. Therefore, the sides
of the balloons that were not rubbed will tend to be closer together. After
you have rubbed the entire balloon, it will be difficult to get rid of the
charge. If you were going to do this experiment, it might be best to rub half
the balloon first and do that experiment, before rubbing the entire balloon.
- By spraying water droplets on the balloons, charge is carried away from
the balloons, which leaves them neutral. This is a good way to neutralize
the balloons. As they become neutral, they will fall back together but will
not be attracted to each other. Another way to neutralize the balloons is
to touch them with a moist or damp hand. One needs to remember that only where
the balloons are wet is where the charges are carried away. The part of the
balloon that is not wet will still attract to the other balloon where it is
- Damp weather reduces the amount of electrical charge, because just like
the mist from the spray bottle, the water droplets carry the charge away from
- It is best to do static electricity experiments in the winter when the
humidity is less. (Adapted from Invitations to Science Inquiry, 2nd
ed. by Tik L. Liem, Activity 9.10)
An electroscope is a device that shows charge is present. By touching an object
to an electroscope (which initially is neutral), charge may be transferred to
the electroscope, which then indicates in some way that charge is present. Let
the students work in groups and have the students make a new design on paper
or actually build an electroscope. They can use different charged objects to
show that their electroscopes work. If they are designing on paper or building
one, ask them to write down the purpose of the different parts (bottle, stopper,
wire, foil, and charged object). If building an electroscope, let the students
try out different things to see what works and what doesn't.
Children with specal needs
Adapt as needed to children who have physical disabilities. These children
may need help blowing up the balloons, tying the thread to the balloon, and
rubbing the balloon with the wool. As always ask your resource teacher for additional
help if you need it.
Student Activity #3 - Static Electricity with Salt and Pepper
- Pepper shaker
- Salt shaker
- Piece of wool, silk, or fake fur
- Clear plastic ruler, or plastic rod
- Piece of paper
- Have the students shake out some salt and pepper on a white sheet of paper
(no more than a teaspoon each).
- Use a pencil's eraser top or pen top to mix the salt and pepper together.
- Take the plastic ruler/rod and rub it with the wool/fake fur.
- Approach the salt and pepper very slowly with the ruler from above. Observe
- Explain what happens after you rub the ruler.
- Why does that happen?
- Why did the pepper jump to the ruler before the salt?
- Can you think of other ways to separate this mixture?
Answers to questions
- The salt and the pepper jump from the paper to the ruler. The pepper is
more likely to jump to the ruler quicker.
- The plastic surfaces have become charged with static electricity from the
fur, or wool, or silk and therefore are attracting these uncharged particles.
- The pepper jumps first because the pepper is lighter than the salt.
- You can place both the salt and the pepper in water where the salt will
sink and dissolve. The pepper will float and therefore can be skimmed off
Children with special needs
Adapt as needed for children who have physical disabilities. For children with
physical disabilities, you may need to put the salt and pepper in a petri dish
for them. Ask your resource teacher for additional help if you need it.
Click here for further
information on laboratories with students with special needs.
Questions to be completed during the laboratory.
For a copy of just student questions, click here.