Webster's Online Dictionary
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Definition: BLACKBODY RADIATION

Part of Speech Definition
Noun 1. The electromagnetic radiation that would be radiated from an ideal black body; the distribution of energy in the radiated spectrum of a black body depends only on temperature and is determined by Planck's radiation law.[Wordnet].

Source: WordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved.

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Definition: BLACKBODY RADIATION

Part of SpeechDefinition
Noun1. The electromagnetic radiation that would be radiated from an ideal black body; the distribution of energy in the radiated spectrum of a black body depends only on temperature and is determined by Planck's radiation law.[Wordnet].

Source: WordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved.

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Common Expressions: BLACKBODY RADIATION

ExpressionsDefinition
Blackbody radiationThe electromagnetic radiation that would be radiated from an ideal black body; the distribution of energy in the radiated spectrum of a black body depends only on temperature and is determined by Planck's radiation law. Source: Wordnet 3.0 Copyright © 2006 by Princeton University. All rights reserved.

Source: compiled by the editor from various references; see credits.

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Specialty Expressions: BLACKBODY RADIATION

ExpressionsDomainDefinition
Blackbody radiationAerospace1: To remain at thermal equilibrium, an object must re-emit all the radiation that it absorbs. Thus, an object which is good at absorbing radiation must be a good emitter, and an object which absorbs all the radiation which strikes it, a "blackbody", must be the best emitter of all. Of course, a blackbody is not really black as it is emitting radiation, and if its temperature is high enough, it is indeed very bright. The distribution of the radiation emitted by a blackbody is spread across the spectrum according to the Planck function, which expresses the intensity spectrum of radiation as a function of wavelength and of the object's temperature. Integration of the Planck function results in the Stefan-Boltzmann law, which states that the total radiation emitted by a blackbody is proportional to the absolute temperature raised to the fourth power, or T. Alternatively, the Planck function may be differentiated with respect to wavelength to reveal the wavelength at which the emitted radiation will have its maximum intensity; the formula for this is known as Wien's displacement law and it states that the peak wavelength is inversely proportional to temperature. Wien's law indicates that for objects at room temperature, the maximum wavelength is well into the infrared. Only with aid of optical devices can, for example, a human be distinguished from his surroundings by measuring the radiation he is emitting. However, at higher temperatures, the peak wavelength shifts to shorter wavelengths and at around 800 K (~527 C, ~980F) an object glows a dull red. For an object as hot as the surface of the Sun (approx. 6000 K), the peak is in the ultraviolet. True blackbodies are few and far between. The atmosphere is certainly not one, as it does not absorb all the radiation which strikes it. However, below 40km it is sufficiently isotropic that when calculating the atmospheric radiative transfer in a climate model, it is a fairly good approximation to specify that the thermal radiation emitted by the atmosphere and by the surface of the planet may be described by the Planck function. See: absolute temperature, thermal radiation. (references)
  2: Blackbody radiation is produced by an object which is a perfect absorber of heat. Perfect absorbers must also be perfect radiators. For a blackbody at a temperature T, the intensity of radiation emitted I at a particular energy E is given by Plank's law: I (E, T) = 2 E[hc(e - 1)], where h is Planck's constant, k is Boltzmann's constant, and c is the speed of light. (references)
Blackbody radiationPhysicsThe radiation -- the radiance at particular frequencies all across the spectrum -- produced by a blackbody -- that is, a perfect radiator (and absorber) of heat. Physicists had difficulty explaining it until Planck introduced his quantum of action. (references)

Source: compiled by the editor from various references; see credits.

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