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electric light




An electric light is an artificial light produced by a flow of electricity in a wire of gas. In an ordinary light bulb, light is produced by incandescence when a filament, such as tungsten-alloy wire, is heated by an electric current. In a fluorescent tube, the electric current passes through a gas. The gas atoms give off invisible ultraviolet rays. These strike a coating on the inside of the tube, causing it to emit light by fluorescence.


Invention of the light bulb

The first electric light bulb was designed by the British scientist Joseph Wilson Swan. Starting in 1848, he used a carbon filament inside an evacuated glass envelope and by 1860, some 20 years earlier than Thomas Edison, he had produced a workable bulb, though with a short lifetime. His bulbs were used to light the House of Commons in 1881 and the British Museum in 1882.


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   • ELECTRICITY AND MAGNETISM
   • TECHNOLOGY