1. The problem statement, all variables and given/known data . With this problem, how should I set image charges so as to satisfy the same boundary condition? And if possible, could you let me know how can that image charge configuration be deduced? Thanks for reading. 2. Relevant equations 3. The attempt at a solution Well, I first put images charges just at the opposite side of the planar and spherical boundary. But I don't know what to do next.