Type | Transformer |
---|---|
Working principle | Electromagnetic induction |
Invented | Nicholas Callan Charles G. Page (independently, 1836) |
An induction coil or "spark coil" (archaically known as an inductorium or Ruhmkorff coil[1] after Heinrich Rühmkorff) is a type of electrical transformer[2][3][4] used to produce high-voltage pulses from a low-voltage direct current (DC) supply.[1][5] To create the flux changes necessary to induce voltage in the secondary coil, the direct current in the primary coil is repeatedly interrupted by a vibrating mechanical contact called an interrupter.[1] Invented in 1836 by the Irish-Catholic priest Nicholas Callan, also independently by American inventor Charles Grafton Page,[1] the induction coil was the first type of transformer. It was widely used in x-ray machines,[1][6] spark-gap radio transmitters,[1][6] arc lighting and quack medical electrotherapy devices from the 1880s to the 1920s. Today its only common use is as the ignition coils in internal combustion engines and in physics education to demonstrate induction.