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Reference.org
Fluorescent lamp
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<p>A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapor <a href="/facts/Gas-discharge_lamp/SQPgULuM">gas-discharge lamp</a> that uses <a href="/facts/Fluorescence/qsJVT2qP">fluorescence</a> to produce visible light. An electric current in the gas excites mercury vapor, to produce <a href="/facts/Ultraviolet/kncBUqn5">ultraviolet</a> and make a <a href="/facts/Phosphor/vTLjrGDE">phosphor</a> coating in the lamp glow. Fluorescent lamps convert electrical energy into visible light much more efficiently than <a href="/facts/Incandescent_light_bulb/31frjg0A">incandescent lamps</a>, but are less efficient than most <a href="/facts/LED_lamp/kMsxpkk9">LED lamps</a>. The typical <a href="/facts/Luminous_efficacy/ryvu6nvc">luminous efficacy</a> of fluorescent lamps is 50–100 lumens per watt, several times the efficacy of incandescent bulbs with comparable light output (e.g. the luminous efficacy of an incandescent lamp may only be 16 lm/w). </p><p>Fluorescent lamp fixtures are more costly than incandescent lamps because, among other things, they require a <a href="/facts/Electrical_ballast/wI5HEsbh">ballast</a> to regulate <a href="/facts/Electric_current/Dc1xdnUX">current</a> through the lamp, but the initial cost is offset by a much lower running cost. <a href="/facts/Compact_fluorescent_lamp/gRsYSlYD">Compact fluorescent lamps</a> (CFL) made in the same sizes as incandescent lamp bulbs are used as an <a href="/facts/Energy-saving/Sk7d6Dg2">energy-saving</a> alternative to incandescent lamps in homes. </p><p>In the <a href="/facts/United_States/P0sCdLe5">United States</a>, fluorescent lamps are classified as <a href="/facts/Universal_waste/KQWyNY5M">universal waste</a>. The <a href="/facts/United_States_Environmental_Protection_Agency/ghI985SI">United States Environmental Protection Agency</a> recommends that fluorescent lamps be segregated from general waste for <a href="/facts/Recycling/x9X7GAzz">recycling</a> or safe disposal, and some jurisdictions require recycling of them. </p>