The Tesla coil is a kind of transformer (resonant transformer) that operates based on the principle of resonance. It was invented by Nikola Tesla, a Serbian-American scientist, in 1891. It is mainly used to generate alternating current electricity with extremely high voltage but low current and high frequency. The Tesla coil consists of two sets (sometimes three sets) of coupled resonant circuits. The Tesla coil is difficult to define precisely as Nikola Tesla experimented with a large number of different configurations of coils. Tesla carried out innovative experiments with these coils, such as in electrical lighting, fluorescence spectroscopy, X-rays, high-frequency alternating current phenomena, electrotherapy and wireless power transmission, as well as the transmission and reception of radio signals.
