The Physics Factbook
Edited by Glenn Elert -- Written by his students
An educational, Fair Use website
|Young, Robyn & Sessine, Suzanne. World of Chemistry. Farmington Hills, MI: Gale Group, 2000.||"Tungsten-halogen lamps generate light in the visible spectrum (380-800 nm)."||3623 K|
|"Incandescent light." Gale Encyclopedia of Science, 2nd ed. 6 vols. Gale Group, 2001.||"Tungsten-halogen lamps are filled with a halogen … gas and degrade much less over their lifetimes … The temperature is higher (above 5,121°F) in these lamps than in regular lamps, thus providing a higher percentage of visible and ultraviolet output."||3100 K|
|Baum, P. Tungsten Halogen Lamps. 1998.||"High voltage tungsten halogen lamps have a luminous efficacy of about 22 lm/W. Common luminous efficacy is about 30 lm/W and color temperature for studio lighting of 3200 degrees Kelvin …. At the highest practical temperatures, peak radiant flux is at about 850nm …. At about 3000 degrees Kelvin the color temperature is about 68 degrees Kelvin … higher than the true temperature …. The upper limit for the color temperature (as a practical sense considering the requirement for a minimum lamp life) is about 3500 degrees Kelvin."||3130 K
|Hurter, Bill. "The Bowens Copytran (evaluation)." Petersen's Photographic. v13 (July 1984): 72.||"The Copytran has two light sources: a 3200 K quartz-halogen focusing light and a 5600 K daylight-balanced electronic flash with high and low power settings."||3200 K|
|Electric Lamp Company, Tungsten Halogen Lamps.||"Light is produced by a tungsten filament operating at about 3000 K temperature in an atmosphere of inert gases (Krypton, Argon, Nitrogen) to which a halogen (Iodine or Bromine, or both) has been added."||3000 K|
Halogen bulbs are used by many people, although not the majority. They are more expensive than regular light bulbs, but they are more energy efficient. Halogen bulbs consist of inert gases and a halogen gas (bromine or iodine, for example). These gases, along with a small filament of tungsten, are encased in a small quartz envelope. As the bulb is used, the tungsten filament evaporates. The evaporated atoms then react with the halogen gas within the bulb. The compound formed then sticks to the original tungsten filament. In a way this process recycles the tungsten particles which results in a longer lasting bulb. The temperature of the bulb throughout this process is around 3300 K. For this reason, these bulbs can be dangerous when they are lit. Since the hottest part of the bulb, the tungsten filament, is so close to the quartz, it is much hotter than a regular bulb. People can burn themselves if they touch the bulb, and objects can catch fire if the yare too close to it. When handling a halogen bulb while it is off, people are recommended not to touch it with their bare hand, since the oils and salts on their fingers will deposit on the bulb and burn when it is turned on.
Elaine Devora -- 2003
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