His Invention Is Still Current

Nikola Tesla, a Croatian-American physicist and engineer who pioneered the use of alternating current electricity, was born at the stroke of midnight on this day in 1856. Believing he could improve upon a direct-current electric dynamo, Tesla designed and built the first alternating current induction motor in 1883. It was comprised of an iron rotor spinning between stationary coils electrified by two out-of-phase alternating currents, which produced a rotating magnetic field.

Alternating current could be transmitted over greater distances than direct current, a fact that in 1893 persuaded George Westinghouse to buy Tesla's patents and use the system at Niagara Falls to power the city of Buffalo. Most of today's electric machines run on alternating current. Tesla is also known for the Tesla coil, a transformer he designed to produce high-frequency, high-voltage electricity.

[Source: Roy Porter, Ed., The Biographical Dictionary of Scientists (Oxford University Press, ed. 2, 1994).]