Subject: biography, physics
Serbian-born US physicist and electrical engineer who was one of the great pioneers of the use of alternating-current electricity. In particular, he invented the alternating-current induction motor and the high-frequency coil that bears his name.
Tesla was born at midnight between 9 and 10 July 1856 in Smiljan, Croatia (then part of Austria-Hungary). His father was a priest of the Serbian Orthodox Church. Tesla was very clever as a child and grew up with a liking for writing poetry and experimentation. It was intended that he should follow his father and become a priest, but Tesla developed an interest in scientific pursuits while he was at the Real Gymnasium in Karlovac. On leaving school he studied engineering at the Technical University at Graz, Austria. In 1880 he went to the University of Prague to continue his studies but the death of his father caused him to leave without graduating.
In 1881, Tesla went to Budapest as an engineer for a telephone company and a year later took up a similar position in Paris. He went to the USA in 1884, and worked for Thomas Edison for a year before setting up on his own. From 1888, Tesla was associated with the industrialist George Westinghouse, who bought and successfully exploited Tesla's patents, leading to the introduction of alternating current for power transmission. Tesla became a US citizen in 1889, and after 1892, when his mother died, became increasingly withdrawn and eccentric. In 1912 both he and Edison were proposed for the Nobel Prize for Physics but Tesla refused to be associated with Edison, who had conducted an unscrupulous campaign for the adoption of direct current. In the event, neither received the prize. Tesla neglected to patent many of his discoveries and made little profit from them. He lived his last years as a recluse and died in New York on 7 January 1943.
In 1878, during his student days at Graz, Tesla saw a direct-current electric dynamo and motor demonstrated and felt that the machine could be improved by eliminating the commutator and sparking brushes, which were sources of wear. His idea for the induction motor came to him in Budapest four years later. He had the notion of an iron rotor spinning between stationary coils that were electrified by two out-of-phase alternating currents producing a rotating magnetic field. Like many of his other ideas, Tesla mentally developed his motor for all kinds of practical applications before ever a model was built.
Tesla built his first working induction motor while he was on assignment in Strasbourg in 1883. However, he found that he could raise little interest in his inventions in Europe so he set off for New York, where he eventually set up his own laboratory and workshop in 1887 to develop his motor in a practical way. Only months later he applied for and was granted a complicated set of patents covering the generation, transmission, and use of alternating-current electricity. At about the same time he lectured to the American Institute of Electrical Engineers on polyphase alternating current. After learning about the talk, Westinghouse quickly bought Tesla's patents.
Westinghouse was able to back Tesla's ideas and as a demonstration, employed his system for lighting at the 1893 World Columbian Exposition in Chicago. Months later Westinghouse won the contract to generate electricity at Niagara Falls, using Tesla's system to supply local industries and deliver polyphase alternating current to the town of Buffalo 35 km/22 mi distant.
After 1888 Tesla's interests turned to alternating currents at very high frequencies, which he felt might be useful for lighting and for communication. After first using high-frequency alternators for these purposes, he designed what has come to be known as the Tesla coil. This is an air-core transformer with the primary and secondary windings tuned in resonance to produce high-frequency, high-voltage electricity. Using this device, Tesla produced an electric spark 40 m/135 ft long in 1899. He also lit more than 200 lamps over a distance of 40 km/25 mi without the use of intervening wires. Gas-filled tubes are readily energized by high-frequency currents and so lights of this type were easily operated within the field of a large Tesla coil. Characteristic of his way of working, Tesla soon developed all manner of coils that have since found numerous applications in electrical and electronic devices.
Tesla was very interested in the possibility of radio communication and as early as 1897 he demonstrated the remote control of two model boats on the lake in Madison Square Gardens in New York. He extended this to guided weapons, in particular a remote-control torpedo. In 1900 he began to construct a broadcasting station on Long Island in the hope of developing ‘World Wireless’; this eventually proved too expensive for his backers and was abandoned. However, many of his ideas have come to fruition at the hands of others. Tesla also outlined a scheme for detecting ships at sea, which was later developed as radar. One of his most ambitious ideas was to transmit alternating-current electricity to anywhere in the world without wires by using the Earth itself as an enormous oscillator. There were many other inventions, including electrical clocks and turbines, but often they remained in his head, there being no money to put them into practice.
Tesla gave the world one of the most practical devices of all time, the alternating-current induction motor. This, coupled with the distinct advantage that alternating current can be transmitted over much greater distances than direct current, has given the motive power for most of our present-day machines.
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