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The lumen (symbol: lm) is the SI unit of luminous flux.
Definition 1 lm = 1 cd·sr = 1 cd·m2·m–2 SI multiples Explanation If a light source emits one candela of luminous intensity into a solid angle of one steradian, the total luminous flux emitted into that solid angle is one lumen. Alternatively, an isotropic one-candela light source emits a total luminous flux of exactly lumens. The lumen can be thought of casually as a measure of the total "amount" of visible light emitted. A standard 100 watt incandescent light bulb emits approximately 1700 lumens. See luminous efficacy for the specific efficiency of various types of electric light sources. SI photometry units See also | ||||||||
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