The camera lens has an aperture of f and the exposure time is 1/60 s. What will be the new exposure time if the aperture become 1.4 f?

Options

A. `(1)/(42)s`
B. `(1)/(56)s`
C. `(1)/(72)s`
D. `(1)/(31)s`

Explanation

Time of exposure `prop (f - "number")^(2)`
`therefore(t)/(((1)/(60)))=((1.4)/(1))^(2)rArrt=(1.4xx1.4)/(60)approx(1)/(31)s`