Luminous Intensity

A measure of the strength of a source of light. Luminous Intensity is
measured in candela (cd). If in a given direction a source of light emits
monochromatic radiation of frequency 540 x 1012Hz and the radiant
intensity in that direction is 1/683 watt per steradian, then the Luminous
Intensity of the source is 1 candela. One candela is equivalent to one
lumen per steradian.