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A lens having focal length f and apertur...

A lens having focal length f and aperture of diameter d forms an image of intenjsity I. Aperture of diameter `(d)/2`in central region of lens in covered by a black paper. Focal length of lens and intensity of image now will be respectively

A

`f and I/4`

B

`(3f)/4 and I/2`

C

`f and (3I)/4`

D

`f/2 and I/2`

Text Solution

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The correct Answer is:
C
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