What is steradian?

  • (noun): The unit of solid angle adopted under the Systeme International d'Unites.
    Synonyms: sr

Steradian

The steradian (symbol: sr) is the SI unit of solid angle. It is used to quantify two-dimensional angular spans in three-dimensional space, analogously to how the radian quantifies angles in a plane. The name is derived from the Greek stereos for "solid" and the Latin radius for "ray, beam".

Read more about Steradian.

Some articles on steradian:

Radiant Flux - Units
... Radiant intensity Ie watt per steradian W⋅sr−1 M⋅L2⋅T−3 power per unit solid angle ... Spectral intensity Ieλ watt per steradian per metre W⋅sr−1⋅m−1 M⋅L⋅T−3 radiant intensity per wavelength ... Radiance Le watt per steradian per square metre W⋅sr−1⋅m−2 M⋅T−3 power per unit solid angle per unit projected source area ...
Steradian - SI Multiples
... Steradians only go up to 4π ≈ 12.56637, so the large multiples are not usable for the base unit, but could show up in such things as rate of coverage of solid angle, for example ... Earth, relative to Earth (cyan on map) 100 steradian sr Area of Oceania plus Asia excluding Russia, relative to Earth (yellow on map) 10−1 decisteradian ...
Overexposed - Photometric and Radiometric Exposure
... Radiant intensity Ie watt per steradian W⋅sr−1 M⋅L2⋅T−3 power per unit solid angle ... Spectral intensity Ieλ watt per steradian per metre W⋅sr−1⋅m−1 M⋅L⋅T−3 radiant intensity per wavelength ... Radiance Le watt per steradian per square metre W⋅sr−1⋅m−2 M⋅T−3 power per unit solid angle per unit projected source area ...
Radiant Energy - SI Radiometry Units
... Radiant intensity Ie watt per steradian W⋅sr−1 M⋅L2⋅T−3 power per unit solid angle ... Spectral intensity Ieλ watt per steradian per metre W⋅sr−1⋅m−1 M⋅L⋅T−3 radiant intensity per wavelength ... Radiance Le watt per steradian per square metre W⋅sr−1⋅m−2 M⋅T−3 power per unit solid angle per unit projected source area ...
Photometry (optics) - Photometric Quantities - Photometric Versus Radiometric Quantities
... Radiant intensity Ie watt per steradian W⋅sr−1 M⋅L2⋅T−3 power per unit solid angle ... Spectral intensity Ieλ watt per steradian per metre W⋅sr−1⋅m−1 M⋅L⋅T−3 radiant intensity per wavelength ... Radiance Le watt per steradian per square metre W⋅sr−1⋅m−2 M⋅T−3 power per unit solid angle per unit projected source area ...