A metal sphere with radius ra is supported on an insulating stand at the center of a hollow, metal spherical shell with radius rb. There is charge + q on the inner sphere and charge − q on the outer spherical shell as shown below. Take the potential V to be zero when the distance r from the center of the spheres is infinite.(Figure 1) Calculate the potential V(r) for r>rb. (Hint: The net potential is the sum of the potentials due to the individual spheres.) Use ϵ0 as the permittivity of free space and express your answer in terms of some or all of the variables r, ra, rb, q, and any appropriate constants.