Question

A ray of light is incident on a transparent medium at an angle of 60°. The reflected ray of light is found to be completely polarised. Then, the refractive index of the transparent medium is nearly:
1. 1.73
2. 1.62
3. 1.52
4. 1.33

Answer 1

Correct Answer - Option 1 : 1.73

Concept:

The incidence angle at which a refracted light becomes completely polarised is called Brewster's angle which is given by the relation,

\(\frac{μ_2}{μ_1}~=~tan~θ_B\)

For polarised ray μ₁ = μ₂  

where,

μ₁ = refractive index at incidence, 

μ₂ = refractive index of reflected ray, 

θ_B = Angle of incidence

Calculation:

Given:

θ_B = 60° 

The reflected ray of light is found to be completely polarised. So,

μ1 = μ2  = μ

From the given formula we have,

μ = tan 60° 

μ = 1.73