First, sorry if something is not totally clear, i'm translating physics term the best I can! 1. The problem statement, all variables and given/known data A sphere or radius a of permittivity ε2 is placed in a dielectric ε1. Without the sphere, we would have E = E0. We want to find the solution to this problem when ε2 = 1 (vacuum). 2. Relevant equations Seems like I'll need those test functions: V1=-E0 + p/r3 (when r > a) V2=-E2 (when r < a) 3. The attempt at a solution I figured I'll need density of charge of polarization at the surface and the field produced by these charges. So now the thing is my last electrodynamic course was a loonng time ago and I'd kinda need a head start on this one. I'm looking through the Griffith but I can't seem to find anything to help me get this problem started. If you guys have any ideas of links that might help that'd be great! Thanks!