emissivity

[ em-uh-siv-i-tee, ee-muh- ]

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.

emissivity

/ ˌɛm-; ɪmɪˈsɪvɪtɪ /

noun

1. 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 ε

Word History and Origins

Origin of emissivity¹

First recorded in 1875–80; emissive + -ity

Example Sentences

Low-e, for “low emissivity,” refers to a microscopically thin coating of metallic particles that reflect some wavelengths of light while allowing most of the visible wavelengths to pass through.

From Washington Post

Values which are commonly given for the surface emissivity must therefore be accepted with great reserve.

From Project Gutenberg

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

From Project Gutenberg

Although these mantles emitted a brilliant light for a few hours, their light-emissivity was destroyed by carbonization.

From Project Gutenberg