A capacitor is made from two concentric spheres, one with radius 5.50 cm, the other with radius 7.20 cm. (a) What is the capacitance of this set of conductors (in pF)? 25.9 pF (b) If the region between the conductors is filled with a material whose dielectric constant is 6.20, what is the capacitance of the system (in pF)? 161 pF