Correct exposure for a photographic print is 10 s at a distance of one metre from a point source of 20 cd. For an equal fogging of the print placed at a distance of 2 m from a 16 cd source, the necessary time for exposure isA. 100 sB. 25 sC. 50 sD. 75 s

Correct exposure for a photographic print is 10 s at a distance of one

1.	Correct exposure for a photographic print is 10 s at a distance of one metre from a point source of 20 cd. For an equal fogging of the print placed at a distance of 2 m from a 16 cd source, the necessary time for exposure isA. 100 sB. 25 sC. 50 sD. 75 s
Answer» Correct Answer - C (c ) For equal fogging of print, `I_(2)xxt_(2)=I_(1)xxt_(1)` or `L_(2)/r_(2)^(2)xxt_(2)=L_(1)/r_(1)^(2)xxt_(1)` or `16/4xxt_(2)=20/1xx10` `therefore` `t_(2)=50 s`

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Correct exposure for a photographic print is 10 s at a distance of one metre from a point source of 20 cd. For an equal fogging of the print placed at a distance of 2 m from a 16 cd source, the necessary time for exposure isA. 100 sB. 25 sC. 50 sD. 75 s

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