NC State Extension

Lumen – Defined

An empirical measure of the quantity of light. It is based upon the spectral sensitivity of the photosensors in the human eye under high (daytime) light levels. Photometrically it is the luminous flux emitted with a solid angle (1 steradian) by a point source having a uniform luminous intensity of 1 candela.

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Photo of Laura LanghamLaura LanghamEnergy Conservation Program Manager (919) 515-8474 laura_langham@ncsu.eduAgricultural and Human Sciences - NC State University
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