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)""(1)/(2)`
D. `sin^(-1)""(sqrt(3))/(2)`

Answer

4

Explanation

Apply snell's law
`(2)/(sqrt(3)) sinC=1 sin90^(@)`
`Sin C=(sqrt(3))/(2) rArr C=60^(@)`
therefore `r=30^(@)`
again apply snell's law
`1 sintheta=(2)/(sqrt(3))xxsin30^(@)`
`theta="sin"^(-1)(1)/(sqrt(3))`