Question

A rectangular brick of gold sits on a rubber mat between a pair of energized parallel plates. The plates are close to but do not touch the gold brick, creating a uniform electric field across the brick that points to the left. What can be said about the charge on the left surface of the brick?

The left surface is charged negatively.

The left surface is charged positively.

The left surface is neutral.

The left surface's charge cannot be determined without further information.

Answer 1

Force experienced by a negative charge in an Electric field by Coulomb's law is

Force experienced by a negative charge in an electric field is directed in the opposite direction of Electric field.

Given that electric field in the brick points towards left, the electrons will be repelled towards right , leaving the left surface to be positively chaged.

Hence, the left surface of the brick will be positively charged.

The correct option is (2) the left surface is charged positively.