A transparent solid cylindrical rod has a refractive index of `(2)/(sqrt3)`. It is surrounded by air. A light ray is incident at the mid point of one end of the rod as shown in the figure.
The incident angle `theta` for which the light ray grazes along the wall of the rod is

Options

A. `sin^(-1)((2)/(sqrt(3)))`
B. `sin^(-1)((1)/(sqrt(3)))`
C. `sin^(-1)((2)/(3))`
D. `sin^(-1)((sqrt(3))/(2))`

Answer

B

Explanation

By using Snell's law we get `mu = sqrt(1 + sin^(2)theta)`
`implies (2)/(sqrt(3)) = sqrt(1 + sin^(2) theta) implies sin^(2) theta = (1)/(3)`
`"sin"theta = (1)/(sqrt(3)) implies theta = sin^(-1) ((1)/(sqrt(3)))`