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Anything related to the *luminous flux* emitted by a light source. The luminous flux is a physical quantity used in photometry to measure the amount of light power radiated from a light source that can be perceived by the human eye. Its unit of measurement in the SI is the *lumen* (lm).

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Nowadays we see LEDs with 300 lumen per watt luminous efficacy. They still waste a lot of power as heat. Now what is the limit of electricity to light conversion? Say we build an LED with 100% efficie …
asked Feb 21 '18 by tigerkoley