What is the definition of light intensity?
There are many kinds of light intensity, each with its own definition. (1) radiant intensity is electromagnetic power per unit solid angle. It is a measure of source intensity. (2) luminous intensity is wavelength-weighted based on a standardized model of the sensitivity of the human eye. (3) irradiance is electromagnetic power per unit area. It is a measure of received intensity (4) Radiance is the amount of light that passes through a particular area, and falls within a given solid angle in a specified direction (i.e., the amount of light hitting 1 square meter and coming from 1 steradian).
