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When appearing on light bulb packages, brightness means luminous flux, while in other contexts it means luminance. [5] Luminous flux is the total amount of light coming from a source, such as a lighting device. Luminance, the original meaning of brightness, is the amount of light per solid angle coming from an area, such as the sky.
In contrast, the term brightness in astronomy is generally used to refer to an object's apparent brightness: that is, how bright an object appears to an observer. Apparent brightness depends on both the luminosity of the object and the distance between the object and observer, and also on any absorption of light along the path from object to ...
Light with the same radiant intensity at other wavelengths has a lower luminous intensity. The curve which represents the response of the human eye to light is a defined standard function y (λ) or V (λ) established by the International Commission on Illumination (CIE, for Commission Internationale de l'Éclairage ) and standardized in ...
An illustration of light sources from magnitude 1 to 3.5, in 0.5 increments. In astronomy, magnitude is a measure of the brightness of an object, usually in a defined passband. An imprecise but systematic determination of the magnitude of objects was introduced in ancient times by Hipparchus. Magnitude values do not have a unit.
A tea light-type candle, imaged with a luminance camera; false colors indicate luminance levels per the bar on the right (cd/m 2). Luminance is a photometric measure of the luminous intensity per unit area of light travelling in a given direction. [1]
Brightness, the subjective perception elicited by the luminance of a source; Luminance, the photometric equivalent of radiance (lm·sr −1 ·m −2) Photometry (optics), measurement of light, in terms of its perceived brightness to the human eye; Radiometry, measurement of light, in absolute power units; Luminosity
Luminous flux is often used as an objective measure of the useful light emitted by a light source, and is typically reported on the packaging for light bulbs, although it is not always prominent. Consumers commonly compare the luminous flux of different light bulbs since it provides an estimate of the apparent amount of light the bulb will ...
Light, visible light, or visible radiation is electromagnetic radiation that can be perceived by the human eye. [1] Visible light spans the visible spectrum and is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 terahertz .