The power of a biconvex lens is `10` dioptre are the radius of the curvature of each surface is `10 cm`. Then the refractive index of the matieral of the lens is

Options

A. `3/2`
B. `4/3`
C. `9/8`
D. `5/3`

Answer

A

Explanation

(a) Power of a biconvex lens is 10 D.
Radius of curvature of each surface = 10 cm.
`rArr1/R_(f)=(mu-1)[1/R_(1)-1/R_(2)] `
`rArr10=(mu-1)[100/10-(-100/10)]`
`rArr10=(mu-1)[20]`
`rArr(mu-1)=1/2`
`rArr` Refractive index of the material, `mu=3/2`