Emission by a source of artificial light

Total emission: lumens (lm)

Luminous efficacy of a lamp (quantity of lumens emitted compared to the electric power consumed):

lumens per watt (lm/W)

Illumination received on a surface within the sensitivity of the human eye (400-700 nm):

lux (lx) = lm/m2 (equivalent to W/m2)

Example: Illumination on a desk: 300 lx.

Updated: August 25, 2015 — 12:01 pm