Field and Wave Electromagnetics 2nd Edition by David Cheng

Exercise 69

A capacitor consists of two concentric spherical shells of radii R i and R 0. The space between them is filled with a dielectric of relative permittivity r from R i to b(R i b R 0 ) and another dielectric of relative permittivity 2 r from b to R 0.
a) Determine E and D everywhere in terms of an applied voltage V.
b) Determine the capacitance.