Luminous Intensity


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Related to Luminous Intensity: luminous intensity unit, luminous flux

Luminous intensity

The solid angular luminous flux density in a given direction from a light source. It may be considered as the luminous flux on a small surface normal to the given direction, divided by the solid angle (in steradians) which the surface subtends at the source of light. Since the apex of a solid angle is a point, this concept applies exactly only to a point source. The size of the source, however, is often extremely small when compared with the distance from which it is observed, so in practice the luminous flux coming from such a source may be taken as coming from a point. See Candlepower, Photometry

Luminous intensity

The luminous flux emitted from a point per unit solid angle in a particular direction. The luminous intensity is the official base unit for light.

Luminous Intensity

 

a fundamental photometric quantity characterizing a source of visible radiation. It is in general different for different directions from the source. The luminous intensity is equal to the ratio of the luminous flux emitted by the source, in an infinitesimal (that is, very small) solid angle containing the given direction, to the solid angle. The unit of luminous intensity in the International System of Units is the candela. The concept of luminous intensity is applicable only at distances from the source that greatly exceed the source’s dimensions.

luminous intensity

[′lü·mə·nəs in′ten·səd·ē]
(optics)
The luminous flux incident on a small surface which lies in a specified direction from a light source and is normal to this direction, divided by the solid angle (in steradians) which the surface subtends at the source of light. Also known as light intensity.

luminous intensity

The luminous flux per unit solid angle in a specific direction from a point source of light; in practice, an interior source may be considered a point source if the distance exceeds 5 to 10 times the maximum source dimension of the luminaire; in US Customary units, expressed in candlepower; in SI units, expressed in candelas.
References in periodicals archive ?
Given only a photometric data report, it is impossible to know how reported zonal lumens of fewer than 10 lumens (and the luminous intensity values they were based on) were derived from the measured luminous intensity data (which in turn is inferred from the photosensor illuminance measurements).
The current SI is founded on the seven base quantities, assumed to be independent, time, length, mass, electric current, thermodynamic temperature, amount of substance, and luminous intensity, for which the SI base units are the second s, meter m, kilogram kg, ampere A, kelvin K, mole mol, and candela cd, respectively; see Table 1.
The visibility of car lights depends on the density of the fog, the distance between the lights and the observer, the lights' luminous intensity, and the lighting conditions (headlights).
Candlepower is the luminous intensity of lamp or luminaire expressed in candles - a standard candle being the unit of luminous intensity.
Headliner Juliet Stevenson performed "Footfalls" and "Not I" with luminous intensity, and the other performers, Debra Gillett and Nigel Cooke, are equally good.
The quality of Mike Nicol's prose, however, gives to the work as a whole a luminous intensity, a solemnity, that demands a reader's response quite beyond the passive.
In its self-cancelling audacity it manifests, it may be, an exhaustion with style which is itself a new but, in the Eliot oeuvre, a terminal style; and its truest note is that of a melancholy serenity which bids farewell to its symbolist origins and sources, to that poetic of luminous intensity, pleading a recourse to other personal, familial, national and religious pieties and fidelities.
R30T consumes only 15W and emits luminous intensity equivalent to a 75W halogen lamp; R38T consumes 20W and emits luminous intensity equivalent to a 100W halogen lamp.
Simply shifting the curve only changes the angle of the maximum luminous intensity.
Utilizing AllnGaP on GaAs chip technology for high luminous intensity to 2750 [mu]cd typical, the VDMx10x0 and VDMx10A1 Series displays are offered in super red, soft orange, yellow, and green for a wide range of applications.
RP-1 sets a maximum limit on luminous intensity for luminaires installed in office environments, as summarized in Table 1 [IES 2004].
They boast faster turn-on and reaction time compared to filament lamps, yet provide comparable luminous intensity and pure wavelength light for a more uniform illumination.