Question
Download Solution PDFWhich of the following statements about the law of illumination is correct?
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFLaws of illumination
1.) Inverse square law
This law states that the illumination at any point on a plane is directly proportional to the luminous intensity and inversely proportional to the square of the distance of the surface from the source.
\(E={I\over r^2}\)
But the drawback of inverse square law is that this law is only applicable if the light source is considered as a point source.
2.) Lambert's Cosine Law
The law states that illumination at a point on a plane is proportional to the cosine of the angle of light incident and inversely proportional to the square of the distance of the surface from the source.
\(E={I cos\theta \over r^2}\)
Last updated on Jul 1, 2025
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