Problem 34. suppose the plates of a parallel-plate capacitor move closer together iis。s (a) use equation (2.44) to express the amount of work done by clectrostatic by an infinitesimal distance e, as a result of their mutual attraction· forces, in terms of the field e, and the area of the plates, a. (b) use equation (2.39) to express the energy lost by the field in this process. the problem is supposed to be easy, but it contains the embryo of an alternative /derivation of equation (2.44), using conservation of energy.フ ous