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Time of exposure for a photographic prin...

Time of exposure for a photographic print is 10 s, when a lamp of 50 cd is placed at 1 m from it. Then another lamp of luminous intensity `I` is used, and is kept at 2 m from it. If the time of exposure now is 20 sec, the value of `I` is (cd)

A

Directly proportional to the intensity of illumination

B

Independent of intesntiy of illumination

C

Inversely proprtional to the intensity of illumination

D

Proportional to the square root of the intensity of illumination

Text Solution

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The correct Answer is:
C
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