What is "arc lamp"

Lamp \Lamp\ (l[a^]mp), n. [F. lampe, L. lampas, -adis, fr. Gr. ?, ?, torch, fr. ? to give light, to shine. Cf. Lampad, Lantern.]

1. A light-producing vessel, device, instrument or apparatus; formerly referring especially to a vessel with a wick used for the combustion of oil or other inflammable liquid, for the purpose of producing artificial light; also, a similar device using a gas as the combustible fuel; now referring mainly to an electric lamp. See sense [3].

2. Figuratively, anything which enlightens intellectually or morally; anything regarded metaphorically a performing the uses of a lamp.

   Thy word is a lamp unto my feet, and a light unto my path.
   --Ps. cxix. 105.

   Ages elapsed ere Homer's lamp appeared.
   --Cowper.

3. (Elec.) A device or mechanism for producing light by electricity, usually having a glass bulb or tube containing the light-emitting element. Most lamps belong to one of two categories, the Incandescent lamp (See under Incandescent) or the fluorescent lamp. However, see also arc lamp, below.

4. A device that emits radiant energy in the form of heat, infrared, or ultraviolet rays; as, a heat lamp.

   [AE]olipile lamp, a hollow ball of copper containing alcohol which is converted into vapor by a lamp beneath, so as to make a powerful blowpipe flame when the vapor is ignited.
   --Weale.

   Arc lamp (Elec.), a form of lamp in which the voltaic arc is used as the source of light.

   D["e]bereiner's lamp, an apparatus for the instantaneous production of a flame by the spontaneous ignition of a jet of hydrogen on being led over platinum sponge; -- named after the German chemist D["o]bereiner, who invented it. Called also philosopher's lamp.

   Flameless lamp, an aphlogistic lamp.

   Lamp burner, the part of a lamp where the wick is exposed and ignited.
   --Knight.

   Lamp fount, a reservoir for oil, in a lamp.

   Lamp jack. See 2d Jack, n., 4 (l) & (n) .

   Lamp shade, a screen, as of paper, glass, or tin, for softening or obstructing the light of a lamp.

   Lamp shell (Zo["o]l.), any brachiopod shell of the genus Terebratula and allied genera. The name refers to the shape, which is like that of an antique lamp. See Terebratula.

   Safety lamp, a miner's lamp in which the flame is surrounded by fine wire gauze, preventing the kindling of dangerous explosive gases; -- called also, from Sir Humphry Davy the inventor, Davy lamp.

   To smell of the lamp, to bear marks of great study and labor, as a literary composition.

alt. An electric arc arranged so as to produce useful light. n. An electric arc arranged so as to produce useful light.

n. a lamp that produces light when electric current flows across the gap between two electrodes [syn: arc light]

An arc lamp or arc light is a lamp that produces light by an electric arc (also called a voltaic arc). The carbon arc light, which consists of an arc between carbon electrodes in air, invented by Humphry Davy in the first decade of the 1800s, was the first practical electric light. It was widely used starting in the 1870s for street and large building lighting until it was superseded by the incandescent light in the early 20th century. It continued in use in more specialized applications where a high intensity point light source was needed, such as searchlights and movie projectors until after World War II. The carbon arc lamp is now obsolete for all of these purposes and is only still made for very specialized purposes where a high intensity UV source is needed.

The term is now used to refer to gas discharge lamps, which produce light by an arc between metal electrodes through an inert gas in a glass bulb. The common fluorescent lamp is a low-pressure mercury arc lamp. The xenon arc lamp, which produces a high intensity white light, is now used in many of the applications which formerly used the carbon arc, such as movie projectors and searchlights.