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प्रश्न
What is a Polaroid?
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उत्तर
A Polaroid is a material which polarises light. The phenomenon of selective absorption is made use of in the construction of polariods. There are different types of polaroids.
A Polaroid consists of micro crystals of herapathite (an iodosulphate of quinine). Each crystal is a doubly refracting medium, which absorbs the ordinary ray and transmits only the extra ordinary ray. The modern polaroid consists of a large number of ultra microscopic crystals of herapathite embedded with their optic axes, parallel, in a matrix of nitro - cellulose.
Recently, new types of polariod are prepared in which thin film of polyvinyl alcohol is used. These are colourless crystals which transmit more light, and give better polarisation.
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संबंधित प्रश्न
If the polarising angle for a given medium is 60°, then the refractive index of the medium is.................
Why does an unpolarised light incident on a polaroid get linearly polarised ?
Two polaroids P1 and P2 are placed with their pass axes perpendicular to each other. An unpolarised light of intensity Io is incident on P1. A third polaroid P3 is kept in between P1 and P2 such that its pass axis makes an angle of 45° with that of P1. Determine the intensity of light transmitted through P1, P2 and P3
Using the phenomenon of polarisation, show how the transverse nature of light can be demonstrated.
Show, via a suitable diagram, how unpolarised light can be polarised by reflection.
What is the Brewster angle for air to glass transition? (Refractive index of glass = 1.5)
When a low flying aircraft passes overhead, we sometimes notice a slight shaking of the picture on our TV screen. Suggest a possible explanation.
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)`
State two uses of Polaroid.
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 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?
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.
Explain how an unpolarised light gets polarised when incident on the interface separating the two transparent media.
Discuss polarisation by selective absorption.
What is plane polarised light?
What is partially polarised light?
State Brewster’s law.
What is normal focusing?
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?
Polarisation of light is the only phenomenon that establishes ______.
Which of the following phenomena is not common to sound and light waves?
Can reflection result in plane polarised light if the light is incident on the interface from the side with higher refractive index?
Figure shown a two slit arrangement with a source which emits unpolarised light. P is a polariser with axis whose direction is not given. If I0 is the intensity of the principal maxima when no polariser is present, calculate in the present case, the intensity of the principal maxima as well as of the first minima.
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 ______.
