In air-conditioned buildings, for example, electricity must be purchased to remove the heat produced by interior lighting, so owners pay twice, once to make the unwanted heat and once to remove it. Heat from light bulbs is often undesirable. The result is that a fluorescent bulb uses much less electricity to provide a given amount of light. Incandescent bulbs convert about 90% of the electricity they consume into heat, whereas fluorescent light bulbs convert only about 30% into heat. A coating on the inside of a glass tube filled with such a gas can absorb the ultraviolet radiation and re-radiate it as visible light. Fluorescent light bulbs operate on the principle that certain gas mixtures, such as mercury vapor mixed with xenon or argon, emit ultra-violet radiation (a form of light invisible to the human eye) when excited by an electric current. Most of the energy consumed by an incandescent bulb is turned into heat, not light. Historical Background and Scientific FoundationsĬonventional light bulbs operate on the principle of heating a small wire or filament until it glows brightly. They last longer than incandescents and, averaged over the lifetime of the device, cost less to run. CFLs contain small amounts of the toxic metal mercury and are more expensive than incandescent light bulbs. Because most electricity worldwide is generated by burning coal, which releases the greenhouse gas carbon dioxide (CO 2), replacing incandescent bulbs with compact fluorescent light bulbs (CFLs) can reduce the amount of greenhouse gases emitted, especially in warmer climates, and have an impact on the amount of global climate change. Large amounts of electricity are used to power light bulbs in industrial countries. Compact Fluorescent Light Bulbs IntroductionĪ compact fluorescent light bulb is a device that creates light using about one fourth as much power as a conventional, incandescent light bulb for a given amount of light.
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