Nikola Tesla is regarded as the father of modern electricity. It is due to his effort that we are able to enjoy the benefits of electricity generated in power stations. He was ahead of his time and had the conviction to challenge the earlier theories. He discovered the phenomena of alternating current or AC and is a source of inspiration to many. Every year New York City celebrates his birthday on July 10 as the "Nikola Tesla Day".
Nikola Tesla was born in Smiljan Lika, on 10 July, 1856. He studied in the Polytechnic Institute in Graz in Austria and the University of Prague. Specializing in Mathematics and Physics, he later changed his mind and opted for electricity
He started his career in a telephone company in Budapest as an electrical engineer in 1881. It was while walking with a friend during his tenure in company that Tesla was struck with the idea of a rotating magnetic field. He tried explaining the phenomena to one of his friends with a diagram of an induction motor using the concept of AC. Later he joined the Continental Edison Company in Paris.
He designed dynamos. But privately he built a prototype of the induction motor in Strassbourg. But his concept did not attract much attention in Europe. Later, Tesla decided to work for the other big stalwart, Thomas Edison in U.S.A. Nikola Tesla was keen on going to USA dreaming of harnessing power from the Niagara Falls.
Before Nikola Tesla came up with the concept of AC, the direct current (DC) was in use. Direct current flows in one direction from a higher potential to a lower potential. But alternating current periodically changes direction. The amplitude of the current increases and then decreases but the maximum value attained each time remains static, yet the direction changes as a result of magnetic polarity change. To understand the phenomena of AC current let us take a point on the wire. Across this point one electron or charge flows in one second from side A to side B and again the electron moves through the same point from side B to side A. The current basically changes its direction through a single point. The change of direction takes place because the wire carrying the current, changes its position in a magnetic field. If a conductor is placed between two opposite poles of a magnet then one finds out more about alternating current (AC). If the conductor is rotated in the field uniformly at a given speed then its sides keep changing its orientation and face the two poles alternately. Magnetic lines are present between the two poles. These magnetic lines of flux are cut by the conductor as it rotates. When the conductor is perpendicular with respect to the magnetic lines the voltage becomes maximum and when it is at zero degree or 180 degrees then the induced voltage becomes zero. So if we plot the graph of the induced voltage against the time period we find a sinusoidal wave generation. This principle is used by generators in power stations to produce AC. The change of direction is so rapid that if connected to a load of an AC circuit, it will always stay in the turned on mode.
In 1884 when Nikola Tesla arrived in New York to work under Thomas Edison, he had a conflict of opinion on the issue of direct and alternating current. According to Nikola Tesla DC power stations along the Atlantic seaboard, were inefficient because huge power losses were incurred. He tried explaining to Edison that the concept of alternating current would make things far simpler and efficient since it is of cyclic nature. The I^2R losses in DC transmission was due to high-voltage. But in AC, the voltage can be stepped up and down by using a transformer. Hence the current can be lowered and losses minimized. But Edison was desperate to fight for his investments made in DC power stations. However he fought a losing battle, because people realized alternating current was the future of electricity transmission.
Nikola Tesla was a visionary and he not only discovered AC current but saw a future in harnessing tidal and solar energy. He developed his polyphase circuit using an AC dynamo, step up and step down transformer with an induction motor at the end. This was perfect for generation of AC and its transmission over long distances. He got his work patented and moved forward.