Editing Arc lamp (section)

{{Short description|Lamp that produces light by an electric arc}}
[[File:Xenon short arc 1.jpg|300px|thumb|The 15 kW [[Xenon arc lamp|xenon short-arc lamp]] used in the [[IMAX]] projection system.]]
[[File:Microscope MercuryArcBulb Detail.jpg|thumb|right|A [[mercury (element)|mercury]] arc lamp from a [[fluorescence microscope]].]]
[[Image:Krypton arc lamp and a xenon flashlamp.JPG|thumb|300px|A krypton long arc lamp (top) is shown above a xenon [[flashtube]]. The two lamps, used for [[laser pumping]], are very different in the shape of the electrodes, in particular, the cathode (on the left).]]

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]].<ref name="Whelan">{{cite web | last = Whelan | first = M. | title = Arc Lamps | work = Resources | publisher = [[Edison Tech Center]] | date = 2013 | url = http://www.edisontechcenter.org/ArcLamps.html | access-date = November 22, 2014 |url-status = live| archive-url = https://web.archive.org/web/20141110140158/http://www.edisontechcenter.org/ArcLamps.html | archive-date = November 10, 2014 }}</ref><ref name="Sussman">{{cite book
 | last1  = Sussman
 | first1 = Herbert L. 
 | title  = Victorian Technology: Invention, Innovation, and the Rise of the Machine
 | publisher = ABC-CLIO
 | date   = 2009
 | pages  = 124
 | url    = https://books.google.com/books?id=sTbPkEXsA5QC&dq=%22arc+lamp%22&pg=PA124
 | doi    = 
 | id     = 
 | isbn   = 9780275991692
 }}</ref>  It was widely used starting in the 1870s for street and large building lighting until it was superseded by the [[incandescent light]] in the early 20th century.<ref name="Whelan" />  It continued in use in more specialized applications where a high intensity point light source was needed, such as [[searchlight]]s and [[movie projector]]s until after [[World War II]].  The carbon arc lamp is now obsolete for most of these purposes, but it is still used as a source of high intensity [[ultraviolet]] light.

The term is now used for [[gas discharge lamp]]s, which produce light by an arc between metal electrodes through a gas in a glass bulb.  The common [[fluorescent lamp]] is a low-pressure mercury arc lamp.<ref>{{cite book|last=Chen|first=Kao |title=Industrial Power Distribution and Illuminating Systems|publisher=Dekker|location=New York|year=1990|series=Electrical Engineering and Electronics|volume=65|page=350|chapter=Fluorescent Lamps|isbn=978-0-8247-8237-5|quote=The fluorescent lamp is ... activated by ... a low-pressure mercury arc.}}</ref> 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.