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incandescence

 
American Heritage Dictionary:

in·can·des·cence

(ĭn'kən-dĕs'əns) pronunciation
n.
  1. The emission of visible light by a hot object.
  2. The light emitted by an incandescent object.
  3. A high degree of emotion, intensity, or brilliance.

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The emission of visible radiation by a hot body. A theoretically perfect radiator, called a blackbody, will emit radiant energy according to Planck's radiation law at any temperature. Prediction of the visual brightness requires additional consideration of the sensitivity of the eye, and the radiation will be visible only for temperatures of the blackbody which are above some minimum. The relation between brightness and temperature is plotted in the illustration. As shown, the minimum temperature for incandescence for the dark-adapted eye is about 390°C (730°F). Under these ideal observing conditions, the incandescence appears as a colorless glow. The dull red light commonly associated with incandescence of objects in a lighted room requires a temperature of about 500°C (930°F). See also Blackbody; Heat radiation; Incandescent lamp; Vision.

Relation between brightness of blackbody and temperature.
Relation between brightness of blackbody and temperature.


The emission of visible light as a result of heating.


Electronics Dictionary:

incandescence

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State of a material when heated to the point where it emits light. (red hot or white hot).


Random House Word Menu:

categories related to 'incandescence'

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Random House Word Menu by Stephen Glazier
For a list of words related to incandescence, see:
  • Optics - incandescence: emission of light due to thermal excitation
  • Physical Properties and Changes - incandescence: emission of light by a substance as a result of raising it to a high temperature


Wikipedia on Answers.com:

Incandescence

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Hot metal work glows with visible light. This thermal radiation also extends into the infrared, invisible to the human eye and the camera the image was taken with, but an infrared camera could show it (See Thermography).
The incandescent metal embers of the spark used to light this Bunsen burner emit light ranging in color from white to orange to red or to blue. This change correlates with their temperature as they cool in the air. The flame itself is not incandescent, as its blue color is due to various other atomic and molecular energy transitions. The blue color comes from the quantized transitions that result from the oxidation of CH radicals.

Incandescence is the emission of light (visible electromagnetic radiation) from a hot body as a result of its temperature.[1] The term derives from the Latin verb incandescere, to glow white.[2]

Incandescence is a special case of thermal radiation. Incandescence usually refers specifically to visible light, while thermal radiation refers also to infrared or any other electromagnetic radiation.

For a detailed discussion of the intensity and spectrum (color) of incandescence, see the article: thermal radiation.

Contents

Observation and use

In practice, virtually all solid or liquid substances start to glow around 798 K (525 °C), with a very dull red color, when no chemical reactions take place that produce light as a result of an exothermic process. This limit is called the Draper point. The incandescence does not vanish below that temperature, but it is too weak in the visible spectrum to be perceivable.

At higher temperatures, the substance becomes brighter and its color changes from red towards white.

Incandescence is exploited in incandescent light bulbs, in which a filament is heated to a temperature at which a fraction of the radiation falls in the visible spectrum. The majority of the radiation however, is emitted in the infrared part of the spectrum, rendering incandescent lights relatively inefficient as a light source.[3] If the filament could be made hotter, efficiency would increase; however, there are currently no materials able to withstand such temperatures which would be appropriate for use in lamps.

More efficient light sources, such as fluorescent lamps and LEDs, do not function by incandescence.

Sunlight is the incandescence of the "white hot" surface of the sun.

Figurative use

The word incandescent is also used figuratively to describe a person who is so angry that they are imagined to glow or burn red hot or white hot.[4]

See also

References

  1. ^ Dionysius Lardner (1833). Treatise on Heat. Longman, Rees, Orme, Brown, Green & Longman. http://books.google.com/?id=jjYIAAAAIAAJ&pg=PA341&dq=incandescence+becomes-luminous. "The state in which a heated body, naturally incapable of emitting light, becomes luminous, is called a state of incandescence." 
  2. ^ John E. Bowman (1856). An Introduction to Practical Chemistry, Including Analysis (Second American ed.). Philadelphia: Blanchard and Lea. http://books.google.com/?id=ffTcf4FGOx4C&pg=PA283&dq=incandesce+date:0-1860. 
  3. ^ William Elgin Wickenden (1910). Illumination and Photometry. McGraw-Hill. http://books.google.com/?id=gVZDAAAAIAAJ&pg=PA3&dq=incandescent+low-efficiency+blackbody. 
  4. ^ Example 1:'...the stadium positively crackled with the incandescent anger of anguished supporters.' Mark Wilson, 'Rangers 1 Unirea 4', Daily Mail, 21 October 2009 [1]. Example 2: '...there's something very funny about incandescent anger.' Mark Fisher, 'Jerry has a cross to bear', The Scotsman, 5 March 2006 [2].

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American Heritage Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.  Read more
McGraw-Hill Science & Technology Encyclopedia. McGraw-Hill Encyclopedia of Science and Technology. Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved.  Read more
McGraw-Hill Dictionary of Architecture & Construction. McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc. All rights reserved.  Read more
Electronics Dictionary. Copyright 2001 by Twysted Pair. All rights reserved.  Read more
Random House Word Menu. © 2010 Write Brothers Inc. Word Menu is a registered trademark of the Estate of Stephen Glazier. Write Brothers Inc. All rights reserved.  Read more
 Rhymes. Oxford University Press. © 2006, 2007 All rights reserved.  Read more
Wikipedia on Answers.com. This article is licensed under the Creative Commons Attribution/Share-Alike License. It uses material from the Wikipedia article Incandescence Read more

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