| Nikola Tesla, born this day or the next in 1856, was a Serbian American inventor and researcher who discovered the rotating magnetic field, the basis of most alternating-current machinery. He immigrated to the United States in 1884 and sold the patent rights to his system of alternating-current dynamos, transformers, and motors to George Westinghouse the following year. In 1891 he invented the Tesla coil, an induction coil widely used in radio technology. |