1. The problem statement, all variables and given/known data Suppose a charge is distributed in a lower half region of a sphere and the upper half has zero charge. What is the potential inside? 2. Relevant equations Poisson Equation? 3. The attempt at a solution My problem here is I don't know how to start, I think laplace equation can't be used because there is charge inside, so it should be poisson's equation. But what exactly should I do?