Question

10C of charge are placed on a spherical conducting shell. A particle with a charge of -3C is placed at the center of the cavity. The net charge on the inner surface of the shell is:

Answer 1

+ 3C.

Step-by-step explanation:

Applying Gauss´s Law to a closed surface encircling the inner surface of the shell, passing through the shell, as the electrostatic field is zero inside a conductor (otherwise there should be moving charges inside the conductor), the net charge enclosed by the surface, must be zero.

So, if we have a -3C charge at the center of the cavity, there must be a +3C charge distributed on the inner surface of the shell, so net charge be zero.