A thin convex lens made from crown glass `(mu = 3/2)`, has focal length f. When it is measured in two different liquids having refractive indices `4/3` and `5/3`, it has the focal lengths `f_(1)` and `f_(2)` repectively. The correct relation between the focal lengths is:

Options

A. `f_(2) gt f "and" f_(1)` become negative
B. `f_(1) "and" f_(2)` both becomes negative
C. `f_(1) = f_(2) lt f`
D. `f_(1) gt f "and" f_(2)` becomes negative

Answer

D

Explanation

`(1)/(f) = ((3//2)/(1) -1)((1)/(R_(1)) - (1)/(R_(2))) ……….(1)`
`(1)/(f) = ((3//2)/(4//3)-1)((1)/(R_(1)) - (1)/(R_(2)))………(2)`
`(1)/(f_(2)) = ((3//2)/(5//3)-1) ((1)/(R_(1)) - (1)/(R_(2))) …….. (3)`