Electric Lighting

The earliest experiments in electric lighting were conducted by British chemist Sir Humphry Davy, who produced electric arcs and who also made a fine platinum wire incandescent in air by passing a current through it. Beginning about 1840 a number of incandescent lamps were patented. None were commercially successful, however, both because the vacuum pumps of the time could not create a vacuum strong enough to protect the wire filaments and because electricity was expensive to obtain. In 1878 and 1879, British inventor Joseph Swan and American inventor Thomas Edison simultaneously developed the carbon-filament lamp. Improved vacuum pumps and the increased availability of electricity made these lamps a success. During the same period various arc lamps were introduced. The first practical arc lamp was installed in a lighthouse at Dungeness, England, in 1862. The American pioneer in electrical engineering Charles Francis Brush produced the first commercially successful arc lamp in 1878. Tungsten filaments were substituted for carbon filaments in incandescent lamps in 1907, and gas-filled incandescent lamps were developed in 1913. The fluorescent lamp was introduced in 1938. See also Lamp.

For most of the 20th century the incandescent light bulb was widely used for lighting in homes. More energy-efficient and longer-lasting fluorescent lamps were adopted for industrial and office use. In 1979 a compact fluorescent bulb that screwed into ordinary light fixtures was introduced. The compact bulbs used 75 percent less electricity and lasted 10 times longer than regular incandescent light bulbs. However, the compact fluorescent bulbs were also much more expensive and had only modest success with consumers.

In 2007 the United States Congress passed the Energy Independence and Security Act, which included provisions that phase out the use of incandescent light bulbs because of their energy inefficiency. By 2014 incandescent bulbs will no longer be sold for home lighting or other uses. American consumers will have a choice of compact fluorescent bulbs or LED lighting fixtures. The use of compact fluorescent bulbs is seen as an interim solution because the bulbs contain mercury and so present a potential pollution hazard. Researchers are developing LED lighting fixtures that are brighter and more energy efficient. Improved LED lighting could be available by the time of the final phase-out of incandescent bulbs.