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.
Origin of emissivity
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Historical Examples of emissivity
The emissivity increases with the temperature, else no state of thermal equilibrium could be reached.
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 temperatureSymbol: ε
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012