Excess charge on an isolated conductor resides entirely on the outer surface.

Excess charge on an isolated conductor resides entirely on the outer surface.

• A. True
• B. False
• C. Not necessarily
• D. Only for spherical conductors

Answer: (A)

In electrostatic equilibrium, the electric field inside a conductor is zero, so any excess charge must move to the boundary of the conductor. The charges repel each other and spread out until the interior feels no field. For an isolated conductor with no charges enclosed in cavities, there is nothing inside the metal to hold charge, so all the excess ends up on the outer surface. This is why the exterior field depends only on the total net charge and the outer surface carries the excess. A small caveat: if there are hollow cavities with charges inside them, charges can induce on the inner surfaces to shield the metal, and the outer surface charge adjusts accordingly. But in the typical case described, excess charge resides entirely on the outer surface.

In electrostatic equilibrium, the electric field inside a conductor is zero, so any excess charge must move to the boundary of the conductor. The charges repel each other and spread out until the interior feels no field. For an isolated conductor with no charges enclosed in cavities, there is nothing inside the metal to hold charge, so all the excess ends up on the outer surface. This is why the exterior field depends only on the total net charge and the outer surface carries the excess. A small caveat: if there are hollow cavities with charges inside them, charges can induce on the inner surfaces to shield the metal, and the outer surface charge adjusts accordingly. But in the typical case described, excess charge resides entirely on the outer surface.