A solid conducting sphere of radius `a` has a net positive charge `2Q`. A conducting spherical shell of inner radius `b` and outer radius `c` is concentric with the solid sphere and has a net charge `-Q`. The surface charge density on the inner and outer surfaces of the spherical shell will be

Options

A. `-(2Q)/(4pib^(2)),(Q)/(4pic^(2))`
B. `-(Q)/(4pib^(2)),(Q)/(4pic^(2))`
C. `0,(Q)/(4pic^(2))`
D. None of these

Answer

A

Explanation

At inner surface `sigma=(-2Q)/(4pib^(2))`
and at outer surface `sigma=(2Q)/(4pi c^(2))`