- a transformer for producing high-voltage alternating current from a low-voltage direct current, consisting essentially of two concentric coils with a common soft-iron core, a primary coil with relatively few windings of heavy wire, and a secondary coil with many turns of fine wire. Excitation of the primary coil by rapidly interrupted or variable current induces high voltage in the secondary coil.
- a transformer for producing a high voltage from a low voltage. It consists of a cylindrical primary winding of few turns, a concentric secondary winding of many turns, and often a common soft-iron coreSometimes shortened to: coil
- An electrical device consisting of a single coil of conductive material, often surrounding a metallic core, designed to establish a strong magnetic field around the coil. Changes in the current flow through the coil cause fluctuations in the magnetic field that induce a voltage across the coil. Induction coils have many applications, especially in circuits that tune to signals of specific frequencies, as in radios. The ability of an induction coil to induce a voltage is called inductance, and is measured in henrys. Compare capacitor.
- A type of transformer that changes a low-voltage direct current to a high-voltage alternating current. Induction coils are used for many purposes, especially as spark coils for firing spark plugs in automobile engines and starting oil burners.