Editing Electric light (section)

=== Fluorescent ===
{{Main|Fluorescent lamp}}
[[File:Leuchtstofflampen-chtaube050409.jpg|thumb|Top, two compact fluorescent lamps. Bottom, two fluorescent tube lamps. A matchstick, left, is shown for scale.]]
[[Fluorescent lamp]]s consist of a glass tube that contains mercury vapour or argon under low pressure. Electricity flowing through the tube causes the gases to give off ultraviolet energy. The inside of the tubes are coated with [[phosphor]]s that give off visible light when struck by ultraviolet [[photon]]s.<ref>{{cite book|last1=Perkowitz|first1=Sidney|last2=Henry|first2=A. Joseph|date=23 November 1998|title=Empire of Light:: A History of Discovery in Science and Art|url=https://books.google.com/books?id=ROHJnk2JOfIC&q=fluorescent+lights+mercury+vapor+excites|publisher=Joseph Henry Press|isbn=978-0-309-06556-6|access-date=10 November 2020|archive-date=20 October 2021|archive-url=https://web.archive.org/web/20211020105531/https://books.google.com/books?id=ROHJnk2JOfIC&q=fluorescent+lights+mercury+vapor+excites|url-status=live}}</ref> They have much higher efficiency than incandescent lamps. For the same amount of light generated, they typically use around one-quarter to one-third the power of an incandescent. The typical [[luminous efficacy]] of fluorescent lighting systems is 50–100 lumens per watt, several times the efficacy of incandescent bulbs with comparable light output. Fluorescent lamp fixtures are more costly than incandescent lamps, because they require a [[electrical ballast|ballast]] to regulate the [[Electric current|current]] through the lamp, but the lower energy cost typically offsets the higher initial cost. [[Compact fluorescent lamp]]s are available in the same popular sizes as incandescent lamps and are used as an [[Energy conservation|energy-saving]] alternative in homes. Because they contain mercury, many fluorescent lamps are classified as [[hazardous waste]]. The [[United States Environmental Protection Agency]] recommends that fluorescent lamps be segregated from general waste for [[recycling]] or safe disposal, and some jurisdictions require recycling of them.<ref>{{cite web|url=http://www.epa.gov/waste/hazard/wastetypes/universal/lamps/index.htm|title=Hazardous Waste|author=United States Environmental Protection Agency, OSWER|website=US EPA|access-date=3 November 2018|date=2015-07-23|archive-date=2015-06-29|archive-url=https://web.archive.org/web/20150629230450/http://www.epa.gov/waste/hazard/wastetypes/universal/lamps/index.htm|url-status=live}}</ref>