The image of an object, forme by a plano-convex lens at a distance of 8m behind the lens, is real and is one-third the size of the object. The wavelength of light inside the lens is `(2)/(3)` times the wavelength is free space. The radius of the curved surface of the lens is

Options

A. 1m
B. 2m
C. 3m
D. 4m

Answer

c.

Explanation

`mu=(lamda_(0))/(lambda_(m))=(3)/(2)`
`rArr (1)/(f)=(mu-1)/(R)=(1)/(2R)`
`rArr (1)/(f)=(1)/(v)-(1)/(u)`
`rArr (1)/(8)-(1)/(-24)=(1)/(2R)rArr (3+1)/(24)=(1)/(2R)rArrR=3m`