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in physics, an ideal black substance that absorbs all and reflects none of the radiant energy falling on it. Lampblack, or powdered carbon, which reflects less than 2% of the radiation falling on it, crudely approximates an ideal blackbody; a material consisting of a carpetlike arrangement of vertically aligned carbon nanotubes was reported in 2008 to have a reflectance of 0.045%. Since a blackbody is a perfect absorber of radiant energy, by the laws of thermodynamics it must also be a perfect emitter of radiation. The distribution according to wavelength of the radiant energy of a blackbody radiator depends on the absolute temperature of the blackbody and not on its internal nature or structure. As the temperature increases, the wavelength at which the energy emitted per second is a maximum decreases. This phenomenon can be seen in the behavior of an ordinary incandescent object, which gives off its maximum radiation at shorter and shorter wavelengths as it becomes hotter and hotter. First it glows in long red wavelengths, then in yellow wavelengths, and finally in short blue wavelengths. In order to explain the spectral distribution of blackbody radiation, Max Planck developed the quantum theoryquantum theory,
modern physical theory concerned with the emission and absorption of energy by matter and with the motion of material particles; the quantum theory and the theory of relativity together form the theoretical basis of modern physics.
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 in 1901. In thermodynamics the principle of the blackbody is used to determine the nature and amount of the energy emitted by a heated object. Black-body radiation has served as an important source of confirmation for the big-bang theory, which holds that the universe was born in a fiery explosion c.13.7 billion years ago (according to current calculations). According to the theory, the explosion should have left a remnant black-body cosmic background radiation that is uniform in all directions and has an equivalent temperature of only a few degrees Kelvin. Such a uniform background, with a temperature of 2.7°K; (see Kelvin temperature scaleKelvin temperature scale,
a temperature scale having an absolute zero below which temperatures do not exist. Absolute zero, or 0°K;, is the temperature at which molecular energy is a minimum, and it corresponds to a temperature of −273.
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), was discovered in 1964 by Arno A. Penzias and Robert L. Wilson, who were awarded the Nobel Prize in Physics in 1978 for their work. Recent data gathered by the NASA satellite Cosmic Microwave Background Explorer (COBE) has revealed small temperature fluctuations in the radiation that are thought to be related to the "seeds" of stars and galaxies.
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An ideal energy radiator, which at any specified temperature emits in each part of the electromagnetic spectrum the maximum energy obtainable per unit time from any radiator due to its temperature alone. A blackbody also absorbs all the energy which falls upon it. The radiation properties of real radiators are limited by two extreme cases—a radiator which reflects all incident radiation, and a radiator which absorbs all incident radiation. Neither case is completely realized in nature. Carbon and soot are examples of radiators which, for practical purposes, absorb all radiation. Both appear black to the eye at room temperature, hence the name blackbody. Often a blackbody is also referred to as a total absorber. See Heat radiation

McGraw-Hill Concise Encyclopedia of Physics. © 2002 by The McGraw-Hill Companies, Inc.


An ideal body which would absorb all incident radiation and reflect none. Also known as hohlraum; ideal radiator.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.


1. A body whose radiation at each wavelength is the maximum possible for any electromagnetic radiator at that temperature.
2. A body that absorbs all light which is incident on it and consequently looks black.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.
References in periodicals archive ?
Blackbody radiation remained, according to Kirchhoff, independent of the nature of the walls [1,2].
Bremer, "Alternative blackbody configurations for infrared calibration of future GOES Imagers and sounders," in Proceedings of International Symposium on Optical Science and Technology, vol.
One cannot expect to reproduce the solar spectrum accurately with a simple blackbody curve; however, we have shown that is possible to extract a reasonably accurate temperature from the best fitting model.
We qualify the measurement by calculating the calibration error, measured for the whole dataset--that is, of about 0.5 K in brightness temperature with respect to the emission of a blackbody at 240 K.
Grigorenko, "Plasmonic blackbody: Strong absorption of light by metal nanoparticles embedded in a dielectric matrix," Phys.
Therefore, due to the spectral distribution of the blackbody emission, which is near to zero at 40 [micro]m wavelength, we can expect substantial confirmation of the emittance results already shown.
He suggested that the radiances of the laboratory blackbody used in the calibration were erroneous.
Finally, we can obtain the corresponding temperature of blackbody radiation, which is the brightness temperature BT (K).
Sample this: Planck getting up in the middle of the night to post a note with the equation for the blackbody spectrum.
The PIRELC, a high-output emitter from Cal Sensors can be used as a steady state or pulsed source of blackbody radiation for near-to-far infrared applications.
When you thermographically calibrate an IR system, you are completing measurements based on effective blackbody radiance and temperature.
But if a warm sample is too thick, it emits all wavelengths, resulting in a featureless "blackbody" spectrum.