STANDARD Physics Lens and Aperture MCQ Question
A lens having focal length f and aperture of diameter d forms an image of intensity I. Aperture of diameter d/2 in central region of lens is covered by a black paper. Focal length of lens and intensity of image now will be respectively
f, I/2
f, I/4
2f, I/2
2f, I/4
Correct Answer
Detailed Explanation
Covering part of the lens does not change the focal length, but reduces the intensity to half.
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