A spherical capacitor consists of an inner conducting sphere of radius Ri, and an outer conductor with a spherical inner wall of radius Ro. The space in between is filled with a dielectric of permittivity, ε. Determine the capacitance as a function of Ri and Ro. If the dielectric is polystyrene of relative permittivity, εr = 2.6, calculate the capacitance of an isolated conducting sphere of a radius 0.4cm(i.e., Ri=0.4cm and Ro goes to infinity). The permittivity of free space is 8.85 * 10^-12.