why do hair stand up when you touch a van de graaff generator?

Question

why? follow up question, what will happen if the insulator you are stepping on is removed. will your hair still stand?

Answer 1

The generator is building up charge that is spreading evenly on the surface of the dome and you that are touching it. Like charge doesn't really like to be near each other, so the electro-static forces causes your hair to move.

If you remove the insulator you will get a nice zap. The insulator keeps you on the same potential ground. Thus no current. Remove the insulator and now there is a potential difference which will only the charge to flow through your body.

Answer 2

Van De Graaff Generator Hair

Answer 3

When you touch a VDG generator, you become charged. Those charges (which are all alike) are in their most energy efficient configuration when they are as far from other like charges as possible. Thus, charges that build up in hairs force the hair up and away from the body to get away from charges that are built up in the body (and the rest of the hair).

If you ground yourself, the charges built up by the VDG generator attempt to build up in the earth; however, the earth is so large that it has little net effect. Thus, the excess charge in you (that will rush away from you in an attempt to move as far as possible away from each other) will be removed and your hair will cease to stand up. (note: there may be some electrostatic discharge when this happens; that is, you may see a spark)