Today in class I rubbed a piece of styrofoam on my head, then put it on a device called an electroscope (see below) and the needle deflected. Explain what happened.
By the way, a common wrong answer says that the needle repels the styrofoam. You know that's wrong because only the top half of the needle goes down; the bottom half goes up.
Explain why when I put the styrofoam on the electroscope, touch the needle with my finger and then remove the styrofoam, the styrofoam deflects.
