The figure shows two concentric spheres of radii a and b. Assume that both spheres are perfectly conducting. The inner and outer spheres contain charges of Q and -Q respectively, and the region between the spheres is filled with a dielectric of permittivity ε₀.
Find the energy of the configuration by using:
(a) W = ∫ E² dt over all space
(b) W = ∫ pV dT