What is Fluorescent lamp?
[[File:OPK_2.jpg|thumb|250px|A traditional tube-shaped fluorescent lamp in a simple fixture]] A '''fluorescent lamp''' is a type of [[lightbulb|electric light]] (lamp) that uses ultraviolet emitted by mercury vapor to excite a phosphor, which emits visible light. There are two general types, traditional fluorescent and [[Compact fluorescent lamp|compact fluorescent]]. This article is about traditional (straight tube shaped) fluorescent lamps. The purchase price of a fluorescent lamp is often much higher than an incandescent lamp of the same output, and the light from fluorescent lamps looks different to light from incandescent lamps.<ref>{{cite web|url=http://www.darksky.org/images/light_spec|title=Spectra of Different Light Sources|accessdate=2007-04-23|archive-date=2006-12-09|archive-url=https://web.archive.org/web/20061209002431/http://www.darksky.org/images/light_spec|url-status=dead}}</ref> Fluorescent lamps have a longer rated life and use less [[energy]] than an incandescent lamp of the same brightness. A fluorescent lamp can save over US$30 in electricity costs over the lamp’s lifetime compared to an incandescent lamp.<ref>{{Cite web |title=Energy Star CFL Introduction Page |url=http://www.energystar.gov/index.cfm?c=cfls.pr_cfls |access-date=2011-09-26 |archive-date=2008-09-16 |archive-url=https://www.webcitation.org/5at4Z0843?url=http://www.energystar.gov/index.cfm?c=cfls.pr_cfls |url-status=dead }}</ref> == How it works == An [[Electricity|electric]] current is applied to [[Mercury (element)|mercury]] vapor inside the tube, causing it to emit [[ultraviolet]] (UV) light. A [[phosphor]] on the walls of the tube [[wikt:absorb|absorb]]s the ultraviolet light. This causes an electron to jump up to an orbital with a higher [[energy]]. When the electron drops back down to its normal orbital, the phosphor re-emits its energy as visible light. == The ballast == [[File:Ballast_for_15W.JPG|thumb|250px|An electronic ballast]] The [[ballast]] prevents too much electricity from flowing through the tube. It also