A negative point charge - is at the center of a hollow insulating spherical shell, which has an inner radius R1 and an outer radius R2. There is a total charge of +7Q spread uniformly throughout the volume of the insulating shell, not just on its surface. Determine the electric field for the following. (Use any variable or symbol stated above along with the following as necessary: r and E
(a) r < R1
(b) R1
(c) R2
