Name: Brewster’s Law
Uploaded: 2019-07-19
Duration: 6 min 57 s
Description: Light is a transverse electromagnetic wave with electric field vectors vibrating in infinite directions perpendicular to the direction of propagation. Let's...

Question

Write definitions of plane of vibration and plane of polarisation.

Explain the working process to obtain plane polarised light by Nicol Prism.

Draw necessary diagram.

Accepted Answer

Plane of vibration : The plane in which the vibration of electric field and magnetic field vibrate it is always perpendicular plane with direction of propagation.

Plane of polarisation : The plane in which remaining vibration vibrate after the process of polarisation. It is also perpendicular plane to the direction of propagation of light.

POLARISATION BY NICOL PRISM :-

Principle : When a thin film of Canada balsam is placed between two calcite pieces, the 0-rays of the unpolarised incident light get eliminated through the phenomenon of total internal reflection while E-rays are transmitted unaffected and emerge as a beam of plane polarised light.

Working : The principal section ACGE of a Nicol prism. The diagonal AG represents the Canada balsam layer. When ray of unpolarised light passes from a portion of the calcite crystal into the layer of canada balsam, it passes from a denser to a rarer medium. When the angle of incidence is greater than the critical angle ( $≃ 69^{°}$ ), the ray is totally reflected and absorbed by a blackened surface. The E-ray is not effected because it is travelling from rarer medium to denser medium. It gets transmitted through the Nicol prism. Hence a ray passes from Nicol prism get polarised.

Write definitions of plane of vibration and plane of polarisation.

Explain the working process to obtain plane polarised light by Nicol Prism.

Draw necessary diagram.

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