A solid dielectric sphere with radius a is placed in vacuum. Its polarization is described as
P(R)=P_{0}(R/a)a_{R}
Please notice that it is not uniform.
1. Discover the bulk charge density of bound charges in the sphere.
2. Discover the surface charge density of bound charges on the sphere.
3. Compute the electrical potential in and outside the sphere.
4. Compute the electrical field in and outside the sphere.