JEE Advanced2008PhysicsRay OpticsActual
A light beam is travelling from Region I to Region IV (refer figure). The refractive index in Region I, II, III and IV are n₀, n₀ 2 , n₀ 6 and n₀ 8 , respectively. The angle of incidence for which the beam just misses entering Region IV is
Options
- A⁻¹ ( 3 4 )
- B⁻¹ ( 1 8 )
- C⁻¹ ( 1 4 )
- D⁻¹ ( 1 3 )
Correct answer
B. ⁻¹ ( 1 8 )
Step-by-step solution
Critical angle from region III to region IV _c= n₀ / 8 n₀ / 6 = 3 4 Now applying Snell's law in region I and region III : n₀ = n₀ 6 _c or aligned & = 1 6 _c= 1 6 ( 3 4 )= 1 8 & = ⁻¹ ( 1 8 ) aligned correct option is (b).