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महाराष्ट्र राज्य शिक्षण मंडळएचएससी विज्ञान (सामान्य) इयत्ता १२ वी

Define Polarisation in Dielectrics. - Physics

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प्रश्न

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.

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उत्तर

If a dielectric (non-polar) molecule is placed in an external electric field, a small induced dipole moment is created because the positive charge in each atom is pushed in the direction of the field and negative charge is pushed in the opposite direction as shown in the figure.

Polarization is the amount of induced surface charge per unit area or the surface density of polarization charges appearing at right angles to applied external electric field.

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2014-2015 (October)

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संबंधित प्रश्‍न

What is a Polaroid?


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


What dose a polaroid consist of?


How does one demonstrate, using a suitable diagram, that unpolarised light when passed through a Polaroid gets polarised?


Using the phenomenon of polarisation, show how the transverse nature of light can be demonstrated.


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


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


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 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.


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


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


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 : 


Green light is 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.


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? 


Light transmitted by Nicol prism is ______.


What is polarisation?


Discuss polarisation by selective absorption.


Mention the types of optically active crystals with example.


Discuss about Nicol prism.


How is polarisation of light obtained by scattering of light?


What is normal focusing?


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


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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.


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