# 17-21-089

luminous efficacy, <of a light source>

ηv; η

quotient of the emitted luminous flux and the power consumed

where Φv is luminous flux and P is the power consumed by the light source

Note 1 to entry: It has to be specified whether or not the power dissipated by auxiliary equipment such as ballasts, if any, is included in the power consumed by the light source.

Note 2 to entry: The luminous efficacy of a light source is expressed in lumen per watt (lm·W−1).

Note 3 to entry: This entry was numbered 845-01-55 in IEC 60050-845:1987.

Note 4 to entry: This entry was numbered 17-729 in CIE S 017:2011.

Publication date: 2020-12