Charged Up About Learning?
Ages: 06 - 10
Materials: Two plastic combs, thread, dry hair and a piece of wool cloth.
Time Required: 30 minutes
When you comb your hair, friction changes the number of electrons on it. The friction takes electrons off the hair and puts them on the comb, especially if your hair is dry. So both your hair and the comb become charged objects.
Well, that's it for the theory. Now you're ready to discover the simple rules that all charged objects must obey.
Before we begin, you should be aware that high humidity reduces static electricity. Best results will be obtained during the drier months.
1. Tie a piece of thread to the center of one comb. Charge the comb by running it through your hair briskly several times. Hang the comb as pictured, being careful not to touch the part of the comb that went through your hair (the charged part).
2. Charge up a second comb in the same way.
3. Bring it near the charged side of the hanging comb, but don't let the two combs touch. Remember what you see. Since both combs had the same charge, you now know two objects with the same charges will repel.
4. Try rubbing the second comb briskly with a piece of wool cloth (sheep hair). As with human hair, the comb removes electrons from the wool, which leaves the wool with a charge opposite that of the comb.
5. Bring the wool cloth near the charged side of the hanging comb. What happens?
Yes! Opposite charges attract.