Concepts Of Physics MCQ Edition [Volume 1]PhysicsGeometrical Optics
A light ray strikes the face AB of a right-angled prism ABC ( = 1.50 ) normally, as depicted in the figure. Determine the maximum value of the angle for which the light ray is totally internally reflected at the surface AC .
Options
- A⁻¹ ( 2 3 )
- B⁻¹ ( 2 3 )
- C⁻¹ ( 1 3 )
- D⁻¹ ( 1 3 )
Correct answer
B. ⁻¹ ( 2 3 )
Step-by-step solution
When the light ray strikes the face AB normally, it enters the prism undeviated and travels parallel to the base BC . At the surface AC , the angle between the incident horizontal ray and the surface AC is . Therefore, the angle of incidence i at the surface AC is given by: i = 90^ - For total internal reflection to occur at the surface AC , the angle of incidence must be greater than or equal to the critical angle _c of the prism: i _c 90^ - _c 90^ - _c The maximum value of is: _ max = 90^ - _c Taking the cosine o