A good photographic print is obtained by an exposure of two seconds at a distance of `20` cm from the lamp. Calculate the time of exposure required to

Question

A good photographic print is obtained by an exposure of two seconds at a distance of `20` cm from the lamp. Calculate the time of exposure required to

A good photographic print is obtained by an exposure of two seconds at a distance of `20` cm from the lamp. Calculate the time of exposure required to get an equally good result at a distance of `40` cm.

Monjur Alahi

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2025-01-04 04:42

1 Answers

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Salim Ahmed Kawsar · Accepted Answer · 2023-02-05T15:29:48+06:00

Salim Ahmed Kawsar

We know that the intensity of light varies inversely as the `("distance")^(2)` . When distance is doubled, the intensity becomes one-fourth . So , the time of exposure should be four times. Hence , time of exposure =`2xx 4 = 8 "s"`

7 views Answered 2023-02-05 15:29