Bibliographic Entry Result

(w/surrounding text) Standardized

Result Chemistry. Prentice Hall, 1996: 443. "Argon atoms prevent the evaporation of the tungsten filament as it heats to a temperature of 3000 °C" 3300 K "Electric Light." World Book Encyclopedia. World Book, 1998: 174-175. "In doing so the electricity heats the filament to more than 2482 °C." 2800 K Bloomfield, Louis A. Incandescent Light Bulbs. How Things Work. University of Virginia. "The tungsten atoms and the filament become extremely hot, typically about 2500 °Celsius." 2800 K "Tungsten." A History of Technology. Oxford, 1958: 98-99. "The development of tungsten, melting at 3410 °C, as a lamp filament began about 1904, and this metal has been used almost exclusively since 1911." <3700 K "Incandescent Lamp." Encarta. Microsoft, 1998. "When electric current flows through the filament, it heats the filament to a temperature of about 3000 °C (about 5000 °F), causing the filament to glow and provide light." 3300 K

Incandescent lamps are the most common sources of electric lighting. The most common incandescent lamp is the conventional household bulb. Incandescent lamps are based on the principle of incandescence, which states that solids and gases emit visible light when heated to a high enough temperature. The bulb consists of a filament positioned inside a glass bulb filled surrounded by an inert gas. This gas is usually composed of a combination of argon and nitrogen, which does not react with the tungsten or the bulb. The gas also acts to extend the life of the filament. The filament is a piece of thin coiled wire and is part of the light bulb that produces the light and is usually made out of tungsten -- a material that can withstand incredibly high temperatures without melting. Despite its miniscule appearance, the filament is about one meter in length wound into a spiral which is then wound again into wider spiral. This spiral design increases the efficiency of the bulb. Electric current flows through the filament when the lamp is turned on. The electrons, which make up the electric current carry energy and collide with the tungsten atoms which then gain kinetic energy. This increases the temperature of the filament to about 2500 °C. As a result the filament glows.

Alexander Eng -- 1999

Bibliographic Entry Result

(w/surrounding text) Standardized

Result Dan MacIsaac, Gary Kanner, and Graydon Anderson. "Basic Physics of the Incandescent Lamp (Lightbulb)." The Physics Teacher. Vol. 37 no. 10 (December 1999): 520-525. "It is extremely difficult to maintain an average temperature higher than about 2900 K" <2900 K

Editor's Supplement -- 1999