Lecture 11: Radiometry & Photometry (27)

I also interpret this equation as E (illuminance of a surface) equals power divided by the area of projecting the surface onto the plane which is perpendicular to the light rays.


This is very similar to the approximate reflection effect we learned a few lectures earlier.


I want confirm does this mean that only luminous flux perpendicular to the surface will contribute to the irradiance?

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