(Smiljan, present-day Croatia, 1856 – New York, 1943) American physicist of Serbian origin. He studied at the universities of Graz (Austria) and Prague. After having worked in various electrical industries in Paris and Budapest, he moved to the United States (1884), where he worked under Thomas A. Edison, then a supporter of direct electric current.
Incessant disputes with Edison forced his departure from the company and his association with George Westinghouse, who bought the patents for his motor and a transformer that facilitated the distribution of this type of current to end users. Both won the battle of energy distribution, since alternating current transportation is cheaper and simpler than direct current. In 1893 his system was adopted by the hydroelectric power station located at Niagara Falls.
Tesla founded an electrotechnical research laboratory in New York, where he discovered the principle of the rotating magnetic field and polyphase alternating current systems. He created the first alternating current induction electric motor and many other electrical devices such as the so-called Tesla mount, a radio frequency transformer in which the primary and secondary are tuned, useful when preselecting the input of a radio receiver. He predicted the possibility of wireless communications in advance of the studies carried out by Marconi, and in his honor the unit of measurement of the intensity of magnetic flux in the international system is called tesla.
His inventions and patents followed one another quite quickly. In 1887, and as a consequence of the discovery carried out by John Hopkinson in 1880, according to which three alternating currents out of phase with each other can be transferred more easily than a normal alternating current, Tesla invented the three-phase current induction motor.
In this motor, the three phases act on the armature so that it rotates by generating a rotating magnetic field. However, the rotor moved with a certain delay with respect to the frequency of the current. Based on this invention, the Swede Ernst Danielson created the synchronous motor in 1902, in which he replaced the armature material, which was not magnetic, with a permanent magnet or electromagnet, which allowed him to obtain a motor that rotated with a number of revolutions per minute equal to the frequency of the current.
In 1891 Tesla invented the coil that bears his name, which consists of a transformer consisting of an air core and primary and secondary spirals in parallel resonance. With this coil he was able to create a high voltage and high frequency field. Two years later he discovered the wave phenomenon called “Tesla light” in high voltage and high frequency alternating currents; By studying these currents, he observed that single-pole incandescent lamps emit light when they are brought close to a conductor through which an electric current passes, and that empty glass tubes shine even if they lack an electrode if they are connected by one of its ends and the other approaches a conductor through which high-frequency current flows. He also realized that the human body is capable of conducting these high-frequency currents without experiencing any damage.