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Besaran cahaya
Satuan besaran cahaya
SI radiometry unitsQuantity Symbol SI unit Abbr. Notes
Radiant energy Q joule J energy
Radiant flux watt Wradiant energy per unit time, also called radiant power
Radiant intensity I watt/steradian W.sr-1 power per unit solid angle
Radiance Lwatt/steradian/square meter
W.sr-
1.m-2
power per unit solid angle per unit projected source area called intensity in some other fields of study
Irradiance E, I watt/square meter W.m-2power incident on a surface, sometimes confusingly called intensity
Radiant exitance / Radiant emittance
M watt/square meter W.m-2 power emitted from a surface
Radiosity J or Jλ watt/square meter W.m-2 emitted plus reflected power leaving a surface
Spectral radianceLλ
orLv
watt/steradian/meter3
orwatt/steradian/square meter/hertz
W.sr-
1.m.-3
orW.sr-
1.m-2.Hz-
1
commonly measured in W.sr-1.m-
2.nm-1
Spectral irradiance
Eλ
orEv
watt/meter3
orwatt/square meter/hertz
W.m-3
orW.m-
2.Hz-1
commonly measured in W.m-2.nm-1
SI photometry unitsQuantity Symbol SI unit Abbr. Notes
Luminous energy Qv lumen second lm.s units are sometimes called talbotsLuminous flux F lumen (= cd.sr) lm also called luminous powerLuminous intensity
Iv candela (=lumen/sr) cd an SI base unit
Luminance Lv candela/square meter cd/m2 units are sometimes called "nits"Illuminance Ev lux (= lm/m2) lx used for light incident on a surfaceLuminous Mv lux (= lm/m2) lx used for light emitted on a surface
emittanceLuminous efficacy
lumen/watt lm/Wratio of luminouos flux to radiant flux
Sumber Cahaya
Radiasi panas (radiasi benda hitam) o bola lampu o matahari o partikel padat bercahaya dalam suhu tinggi(lihat api)
emisi spektral atomik o laser dan masero light emitting diode o lampu gas(lampu neon, lampu air raksa lamps dsb)o api dari gas
percepatan dari partikal bebas bermuatan(biasanya sebuah elektron) o radiasi siklotron o Radiasi Bremsstrahlungo Radiasi Cherenkov
kemoluminesens floresens fosforescence
o tabung sinar katoda bioluminesens sonoluminesens triboluminesens peluruhan radioaktif anihilasi partikel-antipartikel