Tesla Coil

Tesla coil [′tes·lə ‚kȯil]

(electromagnetism)

An air-core transformer used with a spark gap and capacitor to produce a high voltage at a high frequency.

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Tesla Coil 

an electrical transforming device consisting of an air-core transformer, a spark gap, and a capacitor. The primary winding of the transformer consists of a few helical turns of thick copper wire. The secondary winding, which is located within or next to the primary winding, consists of a large number of turns of thin insulated copper wire. The primary winding is connected to an AC source via the spark gap and capacitor. Oscillations of high voltage (up to 7 × 10⁶ volts) and high frequency (up to 1.5 × 10⁵ hertz) are excited in the secondary winding, in which resonance conditions are satisfied.

The Tesla coil was invented in 1891 by N. Tesla. In the early period of the development of radio engineering, it was used at radio stations as a high-frequency oscillator; by the mid-1970’s it was used only for demonstration purposes.