Editing Lux (section)

{{short description|SI derived unit of illuminance}}
{{Other uses|Lux (disambiguation)}}
{{Use dmy dates|date=March 2023|cs1-dates=y}}
{{Infobox unit
| bgcolor    =
| name       = lux
| image      = Lux meter.jpg
| caption    = A lux meter for measuring illuminance 
| standard   = [[SI]]
| quantity   = [[illuminance]]
| symbol     = lx
| units1     = [[SI base unit]]s
| inunits1   = [[candela|cd]]⋅[[steradian|sr]]⋅[[metre|m]]<sup>−2</sup>
| units2     = [[United States customary units|US customary units]]
| inunits2   = 0.0929 [[Foot-candle|fc]]
| units3     = [[Centimetre–gram–second system of units|CGS]] units
| inunits3   = {{val|e=-4|u=[[phot|ph]]}}
}}
The '''lux''' (symbol: '''lx''') is the unit of [[illuminance]], or [[luminous flux]] per unit area, in the [[International System of Units]] (SI).<ref name="SIBrochure9thEd">{{citation |title=The International System of Units (SI) |author=International Bureau of Weights and Measures |author-link=New SI |date=20 May 2019  |edition=9th |isbn=978-92-822-2272-0 |url=https://www.bipm.org/utils/common/pdf/si-brochure/SI-Brochure-9.pdf| archive-url = https://web.archive.org/web/20211018184555/https://www.bipm.org/documents/20126/41483022/SI-Brochure-9.pdf/fcf090b2-04e6-88cc-1149-c3e029ad8232 |archive-date=18 October 2021 |url-status=live}}</ref><ref>{{cite book |last1=CIE |title=CIE S 017:2020 ILV: International Lighting Vocabulary, 2nd edition. |date=2020 |publisher=CIE |edition=2 |url=https://cie.co.at/eilvterm/17-21-085}}</ref> It is equal to one [[lumen (unit)|lumen]] per square metre. In [[photometry (optics)|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 [[radiometry|radiometric]] unit [[Irradiance|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 [[International Organization for Standardization|ISO]].<ref>{{cite book | url=https://www.iso.org/standard/83178.html | title=ISO/CIE 23539:2023 CIE TC 2-93 Photometry — The CIE system of physical photometry | publisher=ISO/CIE | date=2023 | language=en | doi=10.25039/IS0.CIE.23539.2023}}</ref> In English, "lux" is used as both the singular and plural form.<ref>[https://www.nist.gov/pml/special-publication-811/nist-guide-si-chapter-9-rules-and-style-conventions-spelling-unit-names NIST Guide to SI Units. Chapter 9 – Rules and Style Conventions for Spelling Unit Names], National Institute of Standards and Technology.</ref>
The word is derived from the [[Latin]] word for "light", [[wikt:lux|lux]].