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The electro-magnetic motor

Born in Croatia, the engineer Nikola Tesla had a distinguished academic and industrial career in central and eastern Europe before coming to the United States in 1884. Here, while working for the Edison Machine Works and independently, Tesla created his greatest invention, the electro-magnetic motor.

A motor converts electrical energy to mechanical power by using current to make a metallic loop (the "rotor," or "armature") spin around a central shaft. Tesla was convinced that DC ("direct current") motors could be modified to operate without commutators---external switches that reverse the direction of the current in the rotor every 180 degrees to keep it spinning in one direction. In early 1888, working out of his experimental shop in New York, he proved his theory: Tesla built and demonstrated the "induction" or "electro-magnetic" motor (patent #381,968). Tesla's revolutionary motor used a rotating magnetic field, rather than mechanical switches, to spin the rotor. This made unit drives for machines possible, and allowed the more efficient AC power ("alternating current," where the rotor swings back and forth) to become the standard for most office and household appliances. Tesla sold his invention to the recently-founded Westinghouse Electric Company, which might not have flourished without his contributions.

Tesla was also a pioneer in the early days of radio (invented by Guglielmo Marconi at the turn of the century). In the year of Tesla's death (1943), the U.S. Supreme Court ruled that Tesla's patents for the radio superseded those of Marconi: this makes Tesla the father of the second generation of radio.

By the end of his career, Tesla had over 700 inventions and 100 patents to his credit. Though his innovations never made him wealthy, Tesla is rightly renowned to this day as one of the greatest electrical engineers of all time.