A point charge q is placed in a cavity in a metal block. If a charge Q is brought outside the metal, will the charge q feel an electric force?

Question

Philoid · Accepted Answer

Metals are conductors of electric charge, the charge placed in metal will always collect on the surface of the metal. However, it has an electrostatic shielding effect. That is, any charge in a cavity inside the metal block will be completely isolated from the outside world. This is because, if we take a Gaussian surface surrounding the cavity, the charge enclosed is zero. By Gauss’ law,

,

Where

= electric flux, E = electric field, ds = area element, q = charge enclosed,

,

Where

= electric flux, E = electric field, ds = area element, q = charge enclosed,