The space between two concentric conducting spherical shells of radii b = 1.70 cm and a = 1.20 cm is filled with a sub- stance of dielectric constant ?= 23.5. A potential difference V = 73.0 V is applied across the inner and outer shells. Determine (a) the capacitance of the device, (b) the free charge q on the inner shell, and (c) the charge q´induced along the surface of the inner shell.