# Greenlight is an incident at the polarising angle on a certain transparent medium. The angle of refraction is 30°. Find (i) polarising angle, and (ii) refractive index of the medium. - Physics

Greenlight is an incident at the polarising angle on a certain transparent medium. The angle of refraction is 30°.
Find
(i) polarising angle, and
(ii) refractive index of the medium.

#### Solution

(i) when the light is incident at the polarizing angle, the angle of refraction and angle of polarization are related according to the equation,

∠ip + ∠r = 90°

The angle of refraction is given as, 30°. So the angle of polarization, ∠ip = 90° - 30° = 60°

(ii) Applying Snell's law, we can write, the refractive index of the transparent media, mu = sin"i"_"p"/sin "r"

⇒ mu = sin60^@/sin30^@ = (sqrt3/2)/(1/2) = sqrt3

⇒  = mu sqrt3

Concept: Polarisation
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