emissivity
emis·siv·i·ty
noun \ˌem-ə-ˈsiv-ət-ē, ˌē-ˌmis-ˈiv-\plural emis·siv·i·ties
Definition of EMISSIVITY
: the relative power of a surface to emit heat by radiation : the ratio of the radiant energy emitted by a surface to that emitted by a blackbody at the same temperature
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