Question

Explain this statement: "In a static situation, the electric field at the surface of a conductor can have no component parallel to the surface because this would violate the condition that the charges on the surface are at rest." Would this statement be valid for the electric field at the surface of an insulator? Explain your answer and the reason for any differences between the cases of a conductor and an insulator.

Answer 1

Step-by-step explanation:

A component of field parallel to the surface would exert a force on the free electrons in the conductor and cause them to move. In an insulator there are no charges free to move and there is no reason why the electric field at the surface of an insulator can’t have a component parallel to the surface.