tesla coil

noun Electricity.

1. an air-core transformer used to produce high voltages of high-frequency alternating currents.

noun

1. a step-up transformer with an air core, used for producing high voltages at high frequencies. The secondary circuit is tuned to resonate with the primary winding

1. An electrical device that generates extremely high voltages, usually for the purpose of creating dramatic electric arcs and lightning effects or for producing x-rays. Tesla coils use step-up transformers to boost the voltage of a power supply and build up large charges in a capacitor. A spark gap periodically shorts out the capacitor, releasing its charge in huge current flows, that generate extremely high voltages (up to ten million volts) through an open-air transformer.