Question

The power of a biconvex lens is 10 dioptre and the radius of curvature of each surface is 10 cm. Then the refractive index of the material of the lens is, ______.

Options

•  `3/2`

•  `4/3`

•  `9/8`

•  `5/3`

Answer 1

The power of a biconvex lens is 10 dioptre and the radius of curvature of each surface is 10 cm. Then the refractive index of the material of the lens is, `3/2`.

Explanation:

`1/"f" = ("n"-1) (1/"R"_1 - 1/"R"_2)`

As P = `1/("f"" (in m)")` = 10 dioptre

10 = `(" n"-1) (1/0.1 + 1/0.1)`

(n - 1) =`1/2`

n= `3/2`