A hollow conducting sphere of inner radius and outer radius
has a charge Q on its surface. A point charge –q is also placed at the centre of the sphere.
(a) What is the surface charge density on the (i) inner and (ii) outer surface of the sphere ?
(b) Use Gauss’ law of electrostatics to obtain the expression for the electric field at a point lying outside the sphere.
a)
i) Surface charge density on the inner surface
ii) Surface charge density on the outer surface
b)
Let the point outside be at a distance r from the center of the sphere, such that r>r2
Consider a Gaussian surface of radius r, then by Gauss law