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Light Bulb

Light bulbs come in various shapes, sizes, wattages, and types. The most common bulb in use today is the incandescent type. People use incandescent light bulbs to light their homes, offices, yards, and even the interior of their appliances.
The first development in electric lighting was the arc lamp, first demonstrated in 1801 by Sir Humphry Davy, in which an electric current bridges a gap between two carbon rods and forms a bright discharge called an arc. The early lamps of this type had an open arc; later ones, enclosed in glass, were more practicable.
The American electrician Moses G. Farmer developed the incandescent electric lamp, in which an electric current passing through a resistance filament enclosed in a vacuum tube heats the filament until it glows, in 1858-59; his version was not practical. Sir Joseph Swan in England and Thomas Edison in the United States, working independently, developed lamps of this kind; the lamp patented by Edison in 1879 was the first widely marketed incandescent lamp and was the forerunner of the modern lamp that utilizes a filament of drawn tungsten sealed airtight in a glass envelope. The American chemist Irving Langmuir invented a gas-filled incandescent lamp in 1913.
  1. Electric incandescent lamp based on a glowing metallic filament enclosed within a glass shell of a semi-vacuum that contains an inert gas such as nitrogen.
  2. Incandescent lights produce light by heating a suitable material to a high temperature. When any solid or gas is heated, commonly by combustion or resistance to an electric current. Common light bulbs use a tungsten-carbon filament because of its strength and high melt-point of 3,400º.
  3. The bulb requires an airtight seal to contain the gas. An optimum amount of vacuum is necessary to produce the desired amount of light.
  4. A base metallic base holds the glass bulb and tungsten filament. A socket holds the base to make the electrical connection required to produce the light.
Light bulbs are everywhere in our everyday life. They are simple and elegant, and we consider them necessary for modern existence. Light bulbs perform both utilitarian and decorative functions, but by and large, we tend to spend little time thinking about them.
The common incandescent light bulb was revolutionary a little over a century ago, but today they are one of the humble features of modern life we couldn't live without.

Information for this article is from:

The Columbia Electronic Encyclopedia, Sixth Edition Copyright © 2000, Columbia University Press. is a service of Infonautics Copyright © 2001 Infonautics Corporation.All rights reserved.