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 ?
In the afterglow luminescence, the slow component is responsible for the long persistent behavior [19]; it shows that the initial intensity for this term is [[alpha].sub.L], and the decay rate of the luminous intensity is proportional to [[tau].sub.L]; that is, larger values for [[alpha].sub.L] and [[tau].sub.L] would result in a higher intensity for (5).
Hence a decrease of more than 30% on luminous intensity could be expected, as evidenced also in the simulations [11] executed to define the optical design of the LED-based lamp.
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.
Illuminance, the amount of light that actually falls on an object, is intimately related to luminous intensity. Picture that light cone of luminous intensity; more light per unit area will fall on an object that's close to the luminaire than on an object far away.
These two types of lights differ in luminous intensity, although the lack of a significant difference does not allow us to conclude that the brightness of the lights has no effect on distance perception.
At night, the entire building lights up like a huge, free-form Japanese paper lantern, glowing with a softly luminous intensity. Van Velsen's contemporary reinterpretation of a fundamentally introverted building type explores concepts of visual and material lightness, far removed from the historical notion of the cinema as a hulking, opaque bunker.
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.
Simply shifting the curve only changes the angle of the maximum luminous intensity. The total luminous flux is the same in both cases.