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Reference.org
Compact fluorescent lamp
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<p>A compact fluorescent lamp (CFL), also called compact fluorescent light, energy-saving light and compact fluorescent tube, is a <a href="/facts/Fluorescent_lamp/R8SlXCyg">fluorescent lamp</a> designed to replace an <a href="/facts/Incandescent_light_bulb/31frjg0A">incandescent light bulb</a>; some types fit into <a href="/facts/Light_fixture/vjgU4z1f">light fixtures</a> designed for incandescent bulbs. The lamps use a tube that is curved or folded to fit into the space of an incandescent bulb, and a compact <a href="/facts/Electronic_ballast/wI5HEsbh">electronic ballast</a> in the base of the lamp. </p><p>Compared to general-service incandescent lamps giving the same <a href="/facts/Luminous_flux/Sfya3RXh">amount of visible light</a>, CFLs use one-fifth to one-third the electric power, and last eight to fifteen times longer. A CFL has a higher purchase price than an incandescent lamp, but can save over five times its purchase price in electricity costs over the lamp's lifetime. Like all fluorescent lamps, CFLs contain toxic <a href="/facts/Mercury_(element)/WlxfoHva">mercury</a>, which complicates their disposal. In many countries, governments have banned the disposal of CFLs together with regular garbage. These countries have established special collection systems for CFLs and other hazardous waste. </p><p>The principle of operation remains the same as in other <a href="/facts/Fluorescent_lamp/R8SlXCyg">fluorescent lighting</a>: electrons that are bound to mercury atoms are excited to states where they will radiate ultraviolet light as they return to a lower energy level; this emitted ultraviolet light is converted into visible light as it strikes the fluorescent coating. </p><p>CFLs radiate a <a href="/facts/Spectral_power_distribution/fuKAFqtu">spectral power distribution</a> that is different from that of incandescent lamps. Improved <a href="/facts/Phosphor/vTLjrGDE">phosphor</a> formulations have improved the perceived color of the light emitted by CFLs, so that some sources rate the best "soft white" CFLs as subjectively similar in color to standard incandescent lamps. </p><p>White <a href="/facts/LED_lamp/kMsxpkk9">LED lamps</a> compete with CFLs for high-efficiency lighting. <a href="/facts/General_Electric/bBm5CzVY">General Electric</a> has since stopped production of domestic CFL lamps in the United States in favour of LEDs. </p>