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 indiced `4//3` and `5//3`, it has the focal length `f_(1)` and `f_(2)` respectively. The correct ralation between the focal lengths is

Options

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