In the above question if there is air in the object space and water in the image space, then the focal length is

Options

A. 4 R
B. 2 R
C. `3(R)/(2)`
D. `R`

Answer

B

Explanation

`mu_1=1,mu_2=(3)/(2),mu_2=(4)/(3),R_1=R,R_2=-R`
`((4)/(3))/(f)=((3)/(2)-1)/(R)+((4)/(3)-(3)/(2))/(-R)=(1)/(2R)+(1)/(6R)=(3+1)/(6R)=(2)/(3R)`
`(4)/(3f)=(2)/(2R)impliesf=2R`