https://doi.org/10.1351/goldbook.R05115
The measurement of quantities associated with @R05039@. The quantities may also describe the variation of the energy with respect to other variables such as @W06659@, time, position, direction (solid @A00346@), area normal to the light or projected area of emitting or receiving surfaces. If the light is monochromatic, it is sometimes convenient to replace the @R05039@ by the corresponding number of photons (or quanta) which is obtained by dividing the energy by \(\frac{h\ c}{\lambda }\) where \(h\) is the @P04685@, \(c\) the velocity of light and \(\lambda \) the @W06659@ of the light.
See:
intensity
, irradiance
, radiance