Try This at Home: Charged Balloons
Opposite charges attract each other and like charges repel each other.
What You Need
- 2 rubber balloons
- Masking tape
- 2 lengths of string or ribbon, about 1 meter (1 yard) each
- Plastic wrap
What To Do
Make sure you have an adult with you to supervise this experiment.
Blow up both balloons and tie their ends. Label one balloon "A" and the other "B".
Tie each string to the end of a balloon. Tape the other ends of the strings to the ceiling. The balloons should hang approximately half a foot apart.
Make a hypothesis! The balloons should be hanging still now. What do you think will happen if you rub the plastic wrap on balloon A? What will happen when you rub balloon B on your hair?
Rub some plastic wrap briskly against balloon A and then release it so that it hangs freely. What happens?
Now rub both balloons A and B on your hair. What happens now? Was your hypothesis correct? Can you explain what is happening here in terms of the charges on the balloons?
Both balloons started out with equal amounts of positive and negative charge; they were neutral. By rubbing the plastic wrap against balloon A, negatively-charged electrons moved from the balloon to the plastic wrap, leaving behind more positive charge than negative on balloon A. Balloon B remains neutral, but the negatively-charged electrons in B are attracted by the positive charge of balloon A, so some electrons move to the side of balloon B that is closest to A. Opposite charges attract; the negative electrons in balloon B attract the positive charge of balloon A so the two balloons move closer together.
Rubbing the balloons on your hair causes electrons to move from your hair to the balloon. Now, both balloons A and B are negatively charged. Like charges repel; the electrons in balloons A repel the electrons in balloon B so the two balloons move farther apart from each other.
Every second, 50 to 100 lightning bolts strike the ground worldwide.