25. ISO 80000-7 — Light and radiation🔗

The fifth part specified in full is ISO 80000-7, Light and radiation. Every item — all of 7-1.1 … 7-37, including every sub-suffixed item — is catalogued: the speed of light and refractive index, radiant energy and its densities, radiant flux, intensity, and radiance, irradiance, exitance, and exposure, the luminous efficiency and efficacy, the luminous quantities, the photon quantities, colorimetry, colour temperature, the optical material properties, and the attenuation coefficients — each carrying its exact source as data: the part, the printed item designation, the principal quantity symbol, and the coherent SI unit symbol. Only citation locators are recorded; no normative content from the licensed standard is reproduced. The defining mathematics of selected remarks is specified in the sibling module Part7.DefiningRelations.

Light and radiation is where dimension does not classify the kind reaches its widest form, and where the catalogue meets two SI base quantities PhysLib's five-generator Dimension does not carry — luminous intensity and amount of substance. Both are handled by the Finkelstein–Whitehead scale-spanning reduction (the Scale-spanning units chapter, requirement R13), not by a new generator: the candela is the dimension of power, the steradian and the mole are dimension one. So the luminous quantities share the dimensions of their radiant partners — luminous flux ≡ radiant flux, luminance ≡ radiance, illuminance ≡ irradiance — while staying distinct kinds, and a molar quantity drops the mole.