Question

A metal sphere with radius 0.035 m has a charge 5 x10-6 C at its surface. Find the electric field E at the surface, the field at 0.02m out of the surface and the field at 0.02 m within the surface.

Answer 1

The field at the center is

$$E_0=kq/R^2=3.7·10^7\text{ V/m}.$$

The field at 0.02 m out of the surface:

$$E_1=kq/(R+r_1)^2=1.5·10^7\text{ V/m}.$$

The field inside the surface of a conducting metal sphere is zero.