3. This problem refers to Figure 3. There is a solid sphere of radius located at the center of a hollow (infinitely thin) spherical shell of radius L. Suppose the inner solid sphere has a uniform charge density p (this is charge per unit volume), and the outer spherical shell has uniform charge density (this is charge per unit area). By assumption, l < L. Find the electric field at a point which is at radius r, for (a) r < l, (b) l < r < L, and (c) L