Question

There is a circle with a smaller circle inside of it. What's the electric field for the hollow sphere, with an inside radius 'a' and outside radius 'b?'

1. r > b

2. r = b

3. a < r < b

4. r = a

5. r < a

The space between a and b is filled with dense material rho.

Answer 1

(1) Charge enclosed inside the sphere of radius will be

Hence using Gauss theorem,

(2) When r=b, \then

Hence using Gauss theorem,

(c)

Charge enclosed inside the sphere of radius will be

Hence using Gauss theorem,

(4) When r=a

Charge inclosed is 0 hence

(5) In this case also, charge inclosed is zero hence field will be zero.