1. The problem statement, all variables and given/known data The space between two spherical shells kept at potentials V1 and V2, respectively, is filled with a dielectric medium. Find the electrostatic energy on the medium. 2. Relevant equations 3. The attempt at a solution I know how to get the energy if I am given the electric field or the charge and potential, but here I am only given two boundary conditions. I can think ot two approaches: try to obtain the potential field everywhere using the Laplace equation and the boundary conditions, and then obtain the electric field from it, or try to obtain the charge of the spheres by assuming uniformly distributed charge on the spheres and then asking how much charge would be needed to have potentials V1 and V2. Which one should I use, if any?