If in a plano-convex lens, the radius of curvature of the convex surface is 10 cm and the focal length of the lens is 30 cm , then the refractive index of the material of lens will be

Options

A. 1.5
B. 1.66
C. 1.33
D. 3

Answer

C

Explanation

(c ) we have, `1/f=(mu-1)(1/R_(1)-1/R_(2))`
`1/30=(mu-1)(1/10)`
The refractive index of the material of the lens
`mu=4/3=1.33`