Show, via a Suitable Diagram, How Unpolarised Light Can Be Polarised by Reflection. - Physics


Show, via a suitable diagram, how unpolarised light can be polarised by reflection.



An ordinary beam of light on reflection from a transparent medium becomes partially polarised. The degree of polarisation increases as the angle of incidence is increased. At a particular value of angle of incidence, the reflected beam becomes completely polarised. This angle of incidence is called the polarising angle (p).

When light is incident at polarising angle at the interface of a refracting medium, the refractive index of the medium is equal to the tangent of the polarising angle.

μ = tan p


μ → Refractive index of the refracting medium

p → Polarising angle


Concept: Polarisation
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2013-2014 (March) All India Set 3


If the polarising angle for a given medium is 60°, then the refractive index of the medium is.................

What is a Polaroid?

With the help of neat diagram, explain how non-polar dielectric material is polarised in external electric field of increasing intensity. Define polarisation in dielectrics.

Draw a neat labelled diagram showing the plane of vibration and plane of polarisation for polarised light.

For a glass plate as a polariser with refractive index 1.633, calculate the angle of incidence at which light is polarised.

If the critical angle of a medium is sin-1(3/5), find the polarising angle.

Show, using a simple polaroid, that light waves are transverse in nature. Intensity of light coming out of a polaroid does not change irrespective of the orientation of the pass axis of the polaroid. Explain why.

Show, with the help of a diagram, how unpolarised sunlight gets polarised due to scattering.

Two polaroids P1 and P2 are placed with their pass axes perpendicular to each other. An unpolarised light of intensity I0 is incident on P1. A third polaroid P3 is kept in between P1 and P2 such that its pass axis makes an angle of 30° with that of P1. Determine the intensity of light transmitted through P1, P2 and P3

Two polaroids P1 and P2 are placed with their pass axes perpendicular to each other. Unpolarised light of intensity I0 is incident on P1. A third polaroid P3 is kept in between P1 and P2 such that its pass axis makes an angle of 60° with that of P1. Determine the intensity of light transmitted through P1, P2 and P3.

The refractive indices of glass and water w.r.t. air are 3/2 and 4/3 respectively. Determine the refractive index of glass w.r.t. water.

What is the Brewster angle for air to glass transition? (Refractive index of glass = 1.5)

The refractive indices of water for red and violet colours are 1.325 and 1.334 respectively.
Find the difference between the velocities of rays for these two colours in water. (c = 3 × 108 m/s)

A ray of light passes from a vacuum to a medium of refractive index (μ). The angle of
incidence is found to be twice the angle of refraction. The angle of incidence is _______.

A) `cos^(-1)(mu/2)`

B) cos−1(μ)

C)  `2 cos^(-1) (mu/2)`

D) `2 sin^(-1) (mu/2)`

Unpolarised light is passed through a polaroid P1. When this polarised beam passes through another polaroid P2 and if the pass axis of P2 makes angle θ with the pass axis of P1, then write the expression for the polarised beam passing through P2. Draw a plot showing the variation of intensity when θ varies from 0 to 2π.

What is the value of refractive index of a medium of polarising angle 60°?

State two uses of Polaroid.

The glass plate of refractive index 1.732 is to be used as a polarizer, its polarising angle is _______.

Show using a proper diagram how unpolarised light can be linearly polarised by reflection from a transparent glass surface.

With the help of an experiment, state how will you identify whether a given beam of light is polarised or unpolarized?

State any two methods by which ordinary light can be polarised

What does a polaroid consist of? How does it produce a linearly polarised light?

Unpolarised light is incident on a polaroid. How would the intensity of transmitted light change when the polaroid is rotated?

Which of the following properties shows that light is a transverse wave?

A beam of light is incident at the polarizing angle of 35° on a certain glass plate. The refractive index of the glass plate is : 

A ray of light is incident on a transparent medium at a polarizing angle. What is the angle between the reflected ray and the refracted ray?

What is the difference between polarised light and unpolarised light? 

A ray of ordinary light is travelling in air. It is incident on air glass pair at a polarising angle of 56°. Find the angle of refraction in glass.

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

Light transmitted by Nicol prism is ______.

The transverse nature of light is shown in ______.

What is polarisation?

Discuss polarisation by selective absorption.

What is a polariser?

What is a analyser?

What is unpolarised light?

What is partially polarised light?

State and obtain Malus’ law.

List the uses of polaroids.

State Brewster’s law.

What is the angle of polarisation and obtain the equation for an angle of polarisation?

Discuss about pile of plates.

What is double refraction?

Discuss about Nicol prism.

How is polarisation of light obtained by scattering of light?

The reflected light is found to be plane polarised when an unpolarized light falls on a denser medium at 60° with the normal. Find the angle of refraction and critical angle of incidence for total internal reflection in the denser to rarer medium reflection.

A plane mirror produces a magnification of

Polarisation of light is the only phenomenon that establishes ______.

Which of the following phenomena is not common to sound and light waves?

An unpolarized light beam is incident on the polarizer of a polarization experiment and the intensity of light beam emerging from the analyzer is measured as 100 Lumens. Now, if the analyzer is rotated around the horizontal axis (direction of light) by 30° in clockwise direction, the intensity of emerging light will be ______ Lumens.

A polarizer - analyser set is adjusted such that the intensity of light coming out of the analyser is just 10% of the original intensity. Assuming that the polarizer - analyser set does not absorb any light, the angle by which the analyser need to be rotated further to reduce the output intensity to be zero, is ______.


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