luminous flux

Luminous flux

The time rate of flow of light. It is radiant flux in the form of electromagnetic waves which affects the eye or, more strictly, the time rate of flow of radiant energy evaluated according to its capacity to produce visual sensation. The visible spectrum is ordinarily considered to extend from 380 to 760 nanometers in wavelength; therefore, luminous flux is radiant flux in that region of the electromagnetic spectrum. The unit of measure of luminous flux is the lumen. See Photometry

McGraw-Hill Concise Encyclopedia of Physics. © 2002 by The McGraw-Hill Companies, Inc.

Luminous flux

The rate of flow of light, analogous to the rate of flow of a fluid.

Illustrated Dictionary of Architecture Copyright © 2012, 2002, 1998 by The McGraw-Hill Companies, Inc. All rights reserved

luminous flux

[′lü·mə·nəs ′fləks]

(optics)

The time rate of flow of radiant energy, evaluated according to its capacity to produce visual sensations; measured in lumens.

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

luminous flux

The rate-of-flow of radiant energy emitted by a lamp.

McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.

luminous flux

The energy field generated by light. See lumen.

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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Luminous Flux

 

a photometric quantity. Luminous flux is radiant flux—that is, the power of the optical radiation —evaluated with respect to its capacity to produce visual sensation. More precisely, luminous flux is radiant flux evaluated according to its action on a selective optical detector whose spectral sensitivity is defined as a function of the spectral luminous efficiency V(λ), where λ is the wavelength of the light in a vacuum. The unit of luminous flux is the lumen. The relation between the luminous flux Ф_v and the radiant flux Ф_e is given by the equation

Here, K_m is the maximum value of the spectral luminous efficacy; K_m ≈ 680 lumens per watt at a wavelength of 555 nanometers.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.