Experiment with Static Electricity
In this science experiment, kids play with balloons while learning about ions and static electricity.
For younger children, it is enough to demonstrate that sometimes things attract other things, like a balloon that has been rubbed on a sweater will attract tiny bits of paper -- or make your hair stand up.
For older children, this is a great time to start introducing the concepts of atomic structure and electrical charges.
An atom is the smallest unit of matter (that we currently know about . . . ). Atoms are made up of protons, neutrons and electrons. Protons and neutrons are in the nucleus (or center) of the atom while electrons move around outside of the nucleus. Protons have a positive charge, neutrons have a neutral charge, and electrons have a negative charge. For the sake of this discussion, we're going to focus only on protons and electrons. Think of them as opposites: protons are positive, electrons are negative.
Different atoms have different numbers of protons and electrons. When an atom has more protons, it has a positive charge. When an atom has more electrons, it has a negative charge. Atoms with either a positive or negative charge are called ions. Things with opposite charges (positive and negative) attract each other; things with same charges (positive to positive, negative to negative) repel each other. Think about magnetic materials, for example.
Atoms don't always stay the same, however. Electrons make things interesting because they can jump around from atom to atom. And when they move, they change the balance of things -- creating a positive or negative charge where there was none before.
This is what is happening when you create static electricity. When you rub a balloon against a wool sweater, you are making electrons move and creating ions.
Most balloons, by themselves, do not have a charge, and so will not attract or repel anything. (Try this.) The balloon is said to be neutral. But when you rub a balloon against a sweater, some of the electrons jump from the balloon atoms to the sweater atoms. This causes some of the atoms in the balloon to have a negative charge – so now the balloon will attract things with a positive charge (and repel things with a negative charge).
A scientist who studies things like electrical charges and electricity is sometimes called an electrical engineer. Electrical engineers not only study electricity, which is the flow of charge, but also try to figure out ways that people can use electricity. They design better electronics, such as cell phones, digital cameras, and computers. They also work on robots, the lighting and electricity in buildings, radar and navigation, and cars. They have even designed an ionic propulsion system for powering space travel!
- Balloon - 1 per student
- Wool sweater - 1 per class
- Small paper confetti, bits of paper, tissue paper, rice cereal or similar
This activity will work best on a dry day; moisture in the air reduces the effect of the static charge.
Blow up a balloon. (Not too full of air because kids will be pressing on the balloon and you don't want it to pop.)
Gently rub the balloon on a wool sweater for 5-10 seconds.
Now hold the balloon over paper confetti, bits of paper or tissue, rice cereal -- anything light weight. In fact, experimenting is half the fun! You can also use your charged balloon to make your hair stand up!
Your balloon will eventually need to be recharged by rubbing it again.
For a fun variation on this activity, try using twisty balloons!