What is the electric field inside a conductor in electrostatic equilibrium, and why?

What is the electric field inside a conductor in electrostatic equilibrium, and why?

• A. E = 0; charges rearrange to cancel the internal field
• B. E = nonzero constant
• C. E increases with depth
• D. E proportional to distance from surface

Answer: (A)

Inside a conductor in electrostatic equilibrium, the electric field is zero. Free charges rearrange themselves so that any attempt to set up a field inside would push charges to move, and they will keep moving until the interior field is canceled. The result is that all excess charge sits on the surface and the potential throughout the conductor is the same. The external field, if present, comes from the surface charges, but the interior remains field-free. (Note: in a non-static situation with currents, a small internal field can exist, but not in electrostatic equilibrium.)

Inside a conductor in electrostatic equilibrium, the electric field is zero. Free charges rearrange themselves so that any attempt to set up a field inside would push charges to move, and they will keep moving until the interior field is canceled. The result is that all excess charge sits on the surface and the potential throughout the conductor is the same. The external field, if present, comes from the surface charges, but the interior remains field-free. (Note: in a non-static situation with currents, a small internal field can exist, but not in electrostatic equilibrium.)