A conducting sphere that carries a total charge of -3q is placed at the centre of a conducting spherical shell that carries a total charged of +5q. The conductors are in electrostatic equilibrium. The charges on the inner and outer surfaces of the shell are respectively.

Options

A. `+3q, +2q`
B. `+q,+q`
C. `+2q,+3q`
D. `+2q,+7q`

Answer

B

Explanation

Before the conducting sphere is kept inside, the conducting shell has +5q charge on its outer surface. Now keeping the conducting sphere at the centre with charge -3q, induces +3q on the inner surface of the shell and -eq on the outer surface of the shell. This -3q added to already existing +5q gives +2q, wghich is the charge on the outer surface. The charge on the inner surface is the induced charge +3q