When two objects are rubbed against each other, some of the electrons from one object jump to the other. The object that gains electrons becomes more negatively charged; the one that loses electrons becomes more positively charged. The opposite charges attract each other in a way that you can actually see.
One way to collect charge is to comb your hair with a nylon comb or rub it with a balloon. The comb or balloon will become attracted to your hair, while the strands of your hair (all the same charge) repel each other. The comb or balloon will also attract a stream of water, which carries an electrical charge.
Time Required: minutes
- Comb dry hair with a nylon comb or rub it with an inflated latex balloon.
- Turn on the tap so that a narrow stream of water is flowing (1-2 mm across, flowing smoothly).
- Move the balloon or teeth of the comb close to the water (not in it). As you approach the water, the stream will begin to bend toward your comb.
- Experiment! Does the amount of 'bend' depend on how close the comb is to the water? If you adjust the flow, does it affect how much the stream bends? Do combs made from other materials work equally well? How does a comb compare with a balloon? Do you get the same effect from everyone's hair or does some hair release more charge than others? Can you get your hair close enough to the water to repel it without getting it wet?
- This activity will work better when the humidity is low. When humidity is high, water vapor catches some of the electrons that would jump between objects. For the same reason, your hair needs to be completely dry when you comb it.
What You Need:
- water faucet
- nylon comb or latex balloon