Dictionary:

blackbody

  (blăk'bŏd'ē)

A theoretically perfect absorber of all incident radiation.

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 also Heat radiation.

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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.

An object that can absorb and send off radiation with complete efficiency — that is, it reflects (see reflection) none of the radiation that falls on it. The higher the object's temperature, the higher the frequency of the radiation it gives off.