Unit of light: luminous energy emitted per second in a unit solid angle by a source of one candela.
Si unit (symbol lm) of luminous flux (the amount of light passing through an area per second).
The lumen is defined in terms of the light falling on a unit area at a unit distance from a light source of luminous intensity of one candela. One lumen at a wavelength of 5,550 angstroms equals 0.0014706 watts. + prikaži više