Swinging Cereal
What you need:
- a hard rubber or plastic comb, or a balloon
- thread
- small pieces of dry cereal (O-shapes, or puffed rice of wheat)
What do you do?
- Tie a piece of the cereal to one end of a 12 inch piece of thread. Find a place to attach the other end so that the cereal does not hang close to anything else. (You can tape the thread to the edge of a table but check with your parents first.)
- Wash the comb to remove any oils and dry it well.
- Charge the comb by running it through long, dry hair several times, or vigorously rub the comb on a wool sweater.
- Slowly bring the comb near the cereal. It will swing to touch the comb. Hold it still until the cereal jumps away by itself.
- Now try to touch the comb to the cereal again. It will move away as the comb approaches.
How does it work?
Combing your hair moved electrons from your hair to the comb. The comb had a negative charge. The neutral cereal was attracted to it. When they touched, electrons slowly moved from the comb to the cereal. Now both objects had the same negative charge, and the cereal was repelled.
