arc lamp

Electric light that uses the illumination of an electric arc maintained between two electrodes. The English chemist Humphry Davy demonstrated the electric arc in 1802 and electric arc lighting was first introduced by English electrical engineer W E Staite in 1846. The lamp consists of two carbon electrodes, between which a very high voltage is maintained. Electric current arcs (jumps) between the two electrodes, creating a brilliant light. Its main use in recent years has been in cinema projectors.

The lamp incorporates a mechanism for automatically advancing the electrodes as they gradually burn away. Modern arc lamps (for example, searchlights) have the electrodes enclosed in an noble gas (rare gas) such as xenon.