A hollow spherical conductor, carrying a net charge +Q, has inner radius r[1] and outer radius r[2] = 2r[1]. At the center of the sphere is a point charge +Q/2. (a) Write the electric field strength E in all three regions as a function of r. Then determine the potential as a function of r, the distance from the center for (b) r>r[2], (c) r[1]