JEE Advanced2010PhysicsRay OpticsActual
A ray O P of monochromatic light is incident on the face A B of prism A B C D near vertex B at an incident angle of 60^ (see figure). If the refractive index of the material of the prism is 3 , which of the following is (are) correct?
Options
- AThe ray gets totally internally reflected at face C D
- BThe ray comes out through face A D
- CThe angle between the incident ray and the emergent ray is 90^
- DThe angle between the incident ray and the emergent ray is 120^
Correct answer
A. The ray gets totally internally reflected at face C D
Step-by-step solution
aligned & 3 = 60^ r & r=30^ aligned _C= ⁻¹ ( 1 3 ) or _C= 1 3 =0.577 At point Q , angle of incidence inside the prism is i=45^ . Since i= 1 2 is greater than _C= 1 2 , ray gets totally internally reflected at face C D . Path of ray of light after point Q is shown in figure. From the figure, we can see that angle between incident ray O P and emergent ray R S is 90^ . Therefore, correct options are (a), (b) and (c).