A light ray is incident normally on the face AB of a right-angled prism `ABC (mu==1.50)` as shown in figure. What is the largest angle `phi` for which the light ray is totally reflected at the surface AC ?

Options

A. `(sqrt(3))/(2)`
B. `(3)/(4)`
C. `(4)/(3)`
D. `(3sqrt(3))/(4)`

Answer

D

Explanation

`alpha+C=90^(@)impliesC=90^(@)-30^(@)=60^(@)`

For total internal reflaction at point P
`mu_(g)sinC=mu_(L)`
Where, `mu_(g)= "Refractive index of the prism" =(3)/(2)`
`implies mu_(L)=(3)/(2)sin60^(@)=((3)/(2))((sqrt(3))/(2))=(3sqrt(3))/(4)`