1. The problem statement, all variables and given/known data Find the capacitance of an isolated ball-shaped conductor of charge q of radius Ri surrounded by an adjacent concentric layer of dielectric with permittivity E and outside radius R2. 2. Relevant equations 3. The attempt at a solution I haven't understood the very first line. Otherwise everything else is fine. From the first line, it says that we take a Gaussian surface between R1 and R2, and hence we have a charge q enclosed and we integrate this from R2 to R1. This is also fine. But my problem lies in the step where we take a Gaussian surface outside the capacitor and we integrate it from infinity to R2. But how is the charge enclosed q, should'nt it be zero?