Knowledge What is luminous flux?

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Knowledge What is luminous flux?


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Luminous flux is a measure of the flow of visible radiant energy emitted in all directions by a light source. It is a weighted sum of the radiant power at all wavelengths in the visible band. Electromagnetic radiation outside the visible band does not contribute to luminous flux. Unless otherwise indicated, the luminous flux is defined for photopic vision. The SI unit of luminous flux is the lumen (lm).