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The exposure time of a camera lens at t...

The exposure time of a camera lens at the `(f)/(2.8)` setting is `(1)/(200) ` second. The correct time of exposure at `(f)/(5.6)` is

A

0 . 4 sec

B

` 0 . 0 2 sec`

C

`0 . 002` sec

D

`0 .0.4` sec

Text Solution

Verified by Experts

The correct Answer is:
B
Time of exposure `prop ("f . Number")^(2)`
`rArr(t_(2))/(t_(1))=((5.6)/(2.8))^(2)=4`
`t_(2)=4t_(1)=4xx(1)/(200)=(1)/(50)sec=0.2 sec`.
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