Question

A metallic spherical shell has an inner radius R₁ and outer radius R₂. A charge Q is placed at the centre of the spherical cavity. What will be surface charge density on (i) the inner surface, and (ii) the outer surface?

Answer 1

When a charge + Q is placed at the centre of spherical cavity,

The charge induced on the inner surface = – Q

The charge induced on the outer surface = + Q

\(\therefore\) Surface charge density on the inner surface = \(\cfrac{-Q}{4\pi R_1^2}\)

Surface charge density on the outer surface = \(\cfrac{+Q}{4\pi R_2^2}\)