PURPOSE: To show that the charge deposited inside a conductor resides on the outside surface, and the charge inside is zero.
DESCRIPTION: The inside surface of a conducting sphere is connected with a wire to the Van de Graaff generator. The Van de Graaff generator is turned on and a lot of charge is deposited inside the conducting sphere. A proof plane is used to sample the charge on the outside surface of the sphere and the charge sample is placed on the foil electroscope. The leaves of the electroscope deflect to show that there is a charge on the outside of the sphere.
Next, the charge on inside surface is sampled. The proof plane is carefully inserted through a hole in the top of the sphere where it touches the inside surface and is removed. The charge sample is deposited on the foil electroscope. The leaves do not deflect and shows that no charge is on the inside surface.
Repeat the procedure to again sample the outside surface of the sphere to prove that the charge is still there.
EQUIPMENT: Van de Graaf, Dome, Electroscope, proof plane, 45 degree mirror and verticle overhead.
SETUP TIME: 1 hour.