Dictionary of Electrical Engineering

Commonly used terms in the Electrical industry.

(1) the ratio of the input power to the output power. It is a figure of merit for the energy cost effectiveness of a device.
(2) in antennas, the ratio of the power radiated to the input power. This term is sometimes defined with the mismatch loss (1-γ2) included in the total efficiency of the antenna; other times, it is omitted from the calculation.
fin efficiency
a thermal characteristic of an extended surface that relates the heat transfer ability of the additional area to that of the base area.
luminous efficiency
the measure of the display output light luminance for a given input power, usually measured in lumens per watt, which is equivalent to the nit.