The lux (symbol: lx) is the unit of illuminance, or luminous flux per unit area, in the International System of Units (SI). It is equal to one lumen per square metre. In photometry, this is used as a measure of the irradiance, as perceived by the spectrally unequally responding human eye, of light that hits or passes through a surface. It is analogous to the radiometric unit watt per square metre, but with the power at each wavelength weighted according to the luminosity function, a model of human visual brightness perception, standardized by the CIE and ISO. In English, "lux" is used as both
AI overview
Lux is the standard unit for measuring how brightly light illuminates a surface, defined as one lumen of light per square meter. It matters because it accounts for how the human eye actually perceives brightness across different colors of light, making it useful for practical applications like lighting design and photography where human vision is the relevant concern.
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Key facts
- Unit.name
- lux
- Unit.image
- Lux meter.jpg
- Unit.caption
- A lux meter for measuring illuminance
- Unit.standard
- SI
- Unit.quantity
- illuminance
- Unit.symbol
- lx
- Unit.units1
- SI base units
- Unit.inunits1
- cd⋅sr⋅m−2
- Unit.units2
- US customary units
- Unit.inunits2
- 0.0929 fc
- Unit.units3
- CGS units
via Wikipedia infobox
Article
10 sectionsContents
- Explanation
- Illuminance
- Relationship between illuminance and irradiance
- Use in video-camera specifications
- Non-SI units of illuminance
- Legacy Unicode symbol
- SI photometry units
- See also
- References
- External links
The lux (symbol: lx) is the unit of illuminance, or luminous flux per unit area, in the International System of Units (SI). It is equal to one lumen per square metre. In photometry, this is used as a measure of the irradiance, as perceived by the spectrally unequally responding human eye, of light that hits or passes through a surface. It is analogous to the radiometric unit watt per square metre, but with the power at each wavelength weighted according to the luminosity function, a model of human visual brightness perception, standardized by the CIE and ISO. In English, "lux" is used as both the singular and plural form. The word is derived from the Latin word for "light", lux.
==Explanation== ===Illuminance=== Illuminance is a measure of how much luminous flux is spread over a given area. One can think of luminous flux (with the unit lumen) as a measure of the total "amount" of visible light present, and the illuminance as a measure of the intensity of illumination on a surface. A given amount of light will illuminate a surface more dimly if it is spread over a larger area, so illuminance is inversely proportional to area when the luminous flux is held constant.