Problem 7. Suppose you have a solid sphere with a radius R and a spherically symmetric charge density dQ dy = p(r). Find Er(r) (from Gauss's Law) for the electrostatic field(s) at all points in space (both r R) for the two charge density distributions given below. Then find the electrostatic potential(s) at all points in space by directly integrating Er(r) in from r = 0. p(r) R a) A uniform charge density p(r) = po for r