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

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

Answer

A

Explanation

Power of lens, `P` (in dioptre)= `(100)/(f"(in cm)")`
`therefore" "f=(100)/(10)=10` cm
For biconvex lens, `R_(1)=+R_(2), R_(2)=-R_(1)`
According to lens maker's formula
`(1)/(f)=(mu-1)((1)/(R)+(1)/(R)) ,(1)/(f)= (mu-1)((2)/(R))`
`rArr" "(1)/(10)= (mu-1)((2)/(10))rArrmu=(1)/(2)+1 = (3)/(2)`