A conducting solid sphere  (radius r_i) with charge -q is located at the center of a conducting hollowed sphere (radius r_o) with charge +q. Non-conducting supports are used to hold and maintain the solid sphere at the center of the hollowed sphere. Taking potential to be zero at r = ∞, determine the electric potential (V_r) at i) inside the solid sphere ii) between the two spheres iii) Outside the hollowed sphere. Hint: Potential at a point is the sum of potentials from each sphere.