A certain luminous surface obeys Lambert's law. Its luminance is equal to `L`. Find:
Channel: Doubtnut
Date: 2020-08-23

A certain luminous surface obeys Lambert's law. Its luminance is equal to `L`. Find:  (a) the luminous flux emitted by a element `DeltaS` of this surface into a cone whose axis is normal to the given element and whose aperture angle is equal to `theta`,  (b) the luminosity of such a source.