Advertisements
Advertisements
प्रश्न
Can reflection result in plane polarised light if the light is incident on the interface from the side with higher refractive index?
Advertisements
उत्तर
If angle of incidence is equal to Brewster’s angle, the transmitted light is slightly polarised and reflected light is plane polarised.
Polarisation by reflection occurs when the angle of incidence is Brewster's angle.
i.e., `tan i_B = ""^1mu_2 = mu_2/mu_1` where `mu_2 < mu_1`
When the light rays travel in such a medium, the critical angle is
`sin i_C = mu_2/mu_1`, where `mu_2 < mu_1`
As `|tan i_B| > |sin i_C|` for large angles `i_B < i_C`
Thus, the polarisation by reflection occurs definitely.
Important point: Brewster's angle (also known as the polarization angle) is an angle of incidence at which light with a particular polarization is perfectly transmitted through a transparent dielectric surface, with no reflection. When unpolarized light is incident at this angle, the light that is reflected from the surface is therefore perfectly polarized. This special angle of incidence is named after the Scottish physicist Sir David Brewster.
APPEARS IN
संबंधित प्रश्न
For a glass plate as a polariser with refractive index 1.633, calculate the angle of incidence at which light is polarised.
Three identical polaroid sheets P1, P2 and P3 are oriented so that the pass axis of P2 and P3 are inclined at angles of 60° and 90° respectively with the pass axis of P1. A monochromatic source S of unpolarised light of intensity I0 is kept in front of the polaroid sheet P1 as shown in the figure. Determine the intensities of light as observed by the observer at O, when polaroid P3 is rotated with respect to P2 at angles θ = 30° and 60°.
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.
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.
State any two methods by which ordinary light can be polarised
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.
What is polarisation?
What is partially polarised light?
Discuss about Nicol prism.
How is polarisation of light obtained by scattering of light?
An unpolarised light of intensity 32 Wm-2 passes through three Polaroids such that the axes of the first and the last Polaroids are at 90°. What is the angle between the axes of the first and middle Polaroids so that the emerging light has an intensity of only 3 Wm-2?
A plane mirror produces a magnification of
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.
For the same objective, find the ratio of the least separation between two points to be distinguished by a microscope for light of 5000 Å and electrons accelerated through 100 V used as the illuminating substance.
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 ______.
The intensity of transmitted light when a polaroid sheet, placed between two crossed polaroids at 22.5° from the polarization axis of one of the polaroids, is (I0 is the intensity or polarised light after passing through the first polaroid):
