1. The surface of a sphere of radius R has a potential
![](Self Assesment_clip_image002.gif)
. If there are no charges outside the sphere, obtain an expression for the potential outside.
2. A sphere of radius R has a surface potential given by
.Obtain an expression for the potential inside the sphere.
The potential inside has the form
. At r=R, the potential can be expressed in terms of spherical harmonics as
Thus only
terms are there in the expression for the potential. We have,