Luminous energy 2545824 183082408 2008-01-09T01:16:56Z Dromadar 5825584 More proper wording In [[photometry]], '''luminous energy''' is the perceived [[energy]] of [[light]]. This is sometimes also called the '''quantity of light'''. Luminous energy is not the same as the [[radiant energy]], the corresponding objective [[physical quantity]]. This is because the human [[eye]] can only see light in the [[visible spectrum]] and has different sensitivities to [[light]] of different [[wavelength]]s within the spectrum. When adapted for bright conditions ([[photopic vision]]), the eye is most sensitive to light at a [[wavelength]] of 555&nbsp;[[metre|nm]]. Light with the same power at longer or shorter wavelengths has a lower luminous energy. ==Units== The [[SI]] unit of luminous energy is the [[lumen]] [[second]], which is unofficially known as the [[Talbot (photometry)|Talbot]] in honor of [[William Henry Fox Talbot]]. In other [[systems of units]], luminous energy may be expressed in basic units of [[energy]]. ==See also== *[[Radiant energy]] {{SI_light_units}} {{optics-stub}} <!--Category--> [[Category:Physical quantity]] [[Category:Photometry]] <!--Interwiki--> [[de:Lichtmenge]] [[it:Grandezze fotometriche]] [[ja:光度エネルギー]]