Advertisements
Advertisements
प्रश्न
What is the angle of polarisation and obtain the equation for an angle of polarisation?
Advertisements
उत्तर
-
The angle of incidence at which the reflected beam is plane polarised light is called polarising angle (ip)
Polarisation by reflection - When ordinary light is incident on the surface of a transparent medium, the reflected light is partially plane polarised.
- The extent of polarization depends on the angle of incidence.
- For a particular angle of incidence, the reflected light is found to be plane polarised.
- The angle of incidence at which a beam of unpolarised light falling on a transparent surface is reflected as a beam of plane polarised light is called polarising angle or Brewster’s angle. It is denoted by i
- At polarising angle, the reflected transmitted rays are perpendicular to other.
ip + 90° + rp = 180°
rp = 90° – ip
From Snell’s law
`(sin "i"_"p")/(sin "r"_"p")` = n - Where n is the refractive index of the medium with respect to air.
- Substitute the value of r from Equation, we get,
`(sin"I"_"p")/(sin (90^circ - "i"_"p")) = (sin "i"_"p")/(sin "r"_"p")` = n
tan ip = n
This relation is known as Brewster’s law.
APPEARS IN
संबंधित प्रश्न
If the polarising angle for a given medium is 60°, then the refractive index of the medium is.................
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.
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
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)
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.
With the help of an experiment, state how will you identify whether a given beam of light is polarised or unpolarized?
Which of the following properties shows that light is a transverse wave?
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 polarisation?
Discuss polarisation by selective absorption.
What is a polariser?
Discuss about pile of plates.
Mention the types of optically active crystals with example.
Consider a light beam incident from air to a glass slab at Brewster’s angle as shown in figure. A polaroid is placed in the path of the emergent ray at point P and rotated about an axis passing through the centre and perpendicular to the plane of the polaroid.
