A light ray hits the pole of a thin biconvex lens as shown in fig. The angle made by the emergent ray with the optic axis will be approximately

Options

A. `0^(@)`
B. `(1//3)^(@)`
C. `(2//3)^(@)`
D. `2^(@)`

Answer

C

Explanation

From Snell's law `therefore mu"sin" 2^(@) = 2mu "sin"r`
`because theta= 2^(@)` (small angle)

`"sin"2^(@) = 2^(@), mu xx 2^(@) = 2 mu r^(@)`
`r=1^(@)` & `2 mu xx 1^(@) = 3mur',r' = ((2)/(3))^(@)`