Luminous efficacy

The luminous efficacy of a light source is its efficiency or energy efficiency, which is the quotient of luminous flux (lumen) and absorbed electrical power (watt). Thus, a 100 W light bulb that delivers a luminous flux of 1500 lm has a luminous efficacy of 15 lm/W. This means that only part of the electrical power absorbed by a light bulb is converted into visible light radiation. The remaining power is mainly emitted in the infrared range and is thus detectable as thermal radiation.

Related Topics