/blak"bod"ee/, n., pl. blackbodies. Physics.
a hypothetical body that absorbs without reflection all of the electromagnetic radiation incident on its surface. Also called perfect radiator.

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Theoretical surface that absorbs all radiant energy that falls on it, and radiates electromagnetic energy at all frequencies, from radio waves to gamma rays, with an intensity distribution dependent on its temperature.

Because all visible light falling on such a surface is absorbed without reflection, the surface will appear black as long as its temperature is such that its emission peak is not in the visible portion of the spectrum. See also absorption.

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      in physics, a surface that absorbs all radiant energy falling on it. The term arises because incident visible light will be absorbed rather than reflected, and therefore the surface will appear black. The concept of such a perfect absorber of energy is extremely useful in the study of radiation phenomena.

      The best practical blackbody is a small hole in a box with a blackened interior, because practically none of the radiation entering such a hole could escape again, and it would be absorbed inside. A surface covered with lampblack will absorb about 97 percent of the incident light and, for most purposes, can be considered a blackbody. Polished metal surfaces, on the other hand, absorb only about 6 percent of the incident radiation, reflecting the rest.

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Universalium. 2010.

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