JEE PHYSICS MCQ: RAY OPTICS

1 Medium

1 of 1

Application +4 | -1

A satisfactory photographic print is obtained when the exposure time is

10\,\,s

at a distance of

2\,\,m

from a

60\,\,cd

lamp. The time of exposure required for the same quality print at a distance of

4\,\,m

from a

120\,\,cd

lamp is

View answer and explanation

Correct option: D

20\,\,s

Option D (20 s) is correct because the exposure time is directly proportional to the square of the distance and inversely proportional to the luminous intensity.

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