JEE Main20199 Jan 2019Morning ShiftPhysicsWave OpticsActual
Consider a tank made of glass (refractive index 1.5 ) with a thick bottom. It is filled with a liquid of refractive index μ . A student finds that, irrespective of what the incident angle i (see figure) is for a beam of light entering the liquid, the light reflected from the liquid glass interface is never completely polarized. For this to happen, the minimum value of μ is:
Options
- A3 5
- B4 3
- C5 3
- D5 3
Correct answer
A. 3 5
Step-by-step solution
For reflected light not be completely polarized, tan r ≠ μ g μ w = 1.5 μ For minimum μ r is maximum. r is maximum when i is maximum i.e. i = 90 o ⇒ sin r = 1 μ ⇒ tan r = 1 μ 2 - 1 ∴ 1 μ 2 - 1 = 1.5 μ ⇒ μ 2 = 2.25 μ 2 - 1 ⇒ 1.25 μ 2 = 2.25 ⇒ μ = 2.25 1.25 = 9 5 = 3 5