- When you rub a plastic ruler through your hair, some of the elctrons are transferred from the ruler to your hair (or the hair to the ruler).
- The hair and the ruler become oppositely charged.
- When you move the ruler away from your hair, you create an electric field.
- Your hair is pulled towards the ruler, and since it is very light, it moves.
What happens if only one of the objects is charged, eg if you bring the charged ruler next to a piece of paper instead? Find out?