An air capacitor is made by using two flat plates, each with area A, separated by a distance d. Then a metal slab having thickness a (less than d) and the same shape and size as the plates is inserted between them, parallel to the plates and not touching either plate. Required:
a. What is the capacitance of this arrangement?
b. Express the capacitance as a multiple of the capacitance Co when the metal slab is not present?
c. Discuss what happens to the capacitance in the limits a--> 0 and a -->d.