Alternating current (AC) is one of two types of electrical flow. The other, Direct current (DC), was the predecessor of alternating current. Following the invention of the electric battery by Alessandro Volta in 1800, the next eighty years saw the invention and development of numerous devices that utilized DC. It was not until 1884 that AC posed a real challenge to DC. Unlike direct current, which flows in one direction, alternating current oscillates forward and backward at a specific frequency, usually 50 or 60 cycles per second (a cycle per second is referred to as Hertz, abbreviated Hz). In other words, the current peaks first in one direction, drops to zero, peaks in the other direction, drops to zero, and then repeats the cycle. AC in North America oscillates at 60 Hz, so it takes only one-sixtieth of a second for a single cycle. In other parts of the world 50 Hz...