Nikola Tesla

Nikola Tesla was born in 1856 in Smiljan, in the Military Frontier of the Austrian Empire (modern Croatia), the son of a Serbian Orthodox priest. He studied engineering in Graz and physics in Prague, then worked for the Continental Edison Company in Paris before emigrating to the United States in 1884 with four cents in his pocket and a letter of introduction to Thomas Edison.

Tesla's central insight was that alternating current — current that reverses direction many times per second — could be generated, transmitted, and converted to mechanical work far more efficiently than Edison's direct current. In 1887-1888 he designed the polyphase AC induction motor and the system of generators, transformers, and transmission lines needed to deliver AC power over long distances. George Westinghouse bought his patents, and the ensuing 'War of Currents' against Edison ended decisively in AC's favour when Westinghouse and Tesla lit the 1893 World's Columbian Exposition in Chicago and built the first large-scale hydroelectric plant at Niagara Falls in 1895.

Tesla was obsessed with resonance. His Tesla coil — a resonant transformer circuit invented in 1891 — produced spectacular high-voltage, high-frequency discharges and became the basis for early radio transmission, neon lighting, and X-ray imaging. He understood that every electrical and mechanical system has a natural frequency, and that driving it at that frequency could produce enormous amplification. He claimed, probably with some exaggeration, to have cracked the plaster of buildings near his Houston Street laboratory by tuning a small mechanical oscillator to the building's resonant frequency.

In his later years Tesla grew increasingly isolated. He announced plans for a wireless energy transmission system, a particle-beam weapon, and other inventions that he never completed. He died alone in a New York hotel room in January 1943. The SI unit of magnetic flux density — the tesla — bears his name.