George Westinghouse was, in my opinion, the only man on this globe who could take my alternating-current system under the circumstances then existing and win the battle against prejudice and money power. He was a pioneer of imposing stature, one of the world's true noblemen of whom America may well be proud and to whom humanity owes an immense debt of gratitude.—Nikola Tesla, inventor of the AC synchronous motor.
The sine wave discussed in Chapter 5 is an example of a periodic function or a function that repeats regularly. When current alternates periodically between positive and negative values it's known as alternating current (AC). AC electricity has some unique properties as we'll soon see.