A convex Lens of focal Length "0.15m" is made of refractive "(3)/(2)" .When it is placed in liquid,its focal Length increases by "0.225m" . Find the refractive index of the liquid.

Options

A. `(7)/(4)`
B. `(5)/(4)`
C. `(9)/(4)`
D. `(3)/(2)`

Answer

B

Explanation

According to lens maker.s formula,
`(1)/(f)=((mu_(2))/(mu_(1))-1)((1)/(R_(1))-(1)/(R_(2)))`
where `mu_(1)` is the refractive index of the medium in which lens is placed and `mu_(2)` is the refractive index of the material of the lens.
`:.` For a convex lens in air
`(1)/(f_(a))=((mu_(g))/(mu_(a))-1)((1)/(R_(1))-(1)/(R_(2)))` ...(i)

For the same convex lens in liquid,