emissivity

American  

[em-uh-siv-i-tee, ee-muh-] / ˌɛm əˈsɪv ɪ ti, ˈi mə- /

noun

Thermodynamics.

1. the ability of a surface to emit radiant energy compared to that of a black body at the same temperature and with the same area.

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emissivity British  

/ ˌɛm-, ɪmɪˈsɪvɪtɪ /

noun

1.  ε.  a measure of the ability of a surface to radiate energy; the ratio of the radiant flux emitted per unit area to that emitted by a black body at the same temperature

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Etymology

Origin of emissivity

First recorded in 1875–80; emissive + -ity

Example Sentences

Efficient cooling requires high reflectivity in the former range to minimise the solar heat gain and high emissivity in the latter range to maximise the radiative heat dissipation.

From Science Daily • Nov. 10, 2023

Reionization after Planck: the derived growth of the cosmic ionizing emissivity now matches the growth of the galaxy UV luminosity density.

From Nature • May 15, 2018

The symbol e stands for the emissivity of the object, which is a measure of how well it radiates.

From Textbooks • Aug. 12, 2015

This high infrared emissivity is why we can so easily feel radiation on our skin.

From Textbooks • Aug. 12, 2015

The emissivity increases with the temperature, else no state of thermal equilibrium could be reached.

From Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 2 "Ehud" to "Electroscope" by Various