✔ 最佳答案
The bits of paper sticks to the balloon. This is caused by static electricity.
When you rub the balloon over your head, the electrons in your hair is transferred (or pulled) into the balloon. As a result the balloon is negatively charged. The negatively charged balloon can then be used to attract the neutral bits of paper.
This trick works best with dry hair, as water molecules can prevent the buildup of eletrical charges.