Video Lecture
Theory For Notes Making
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Objective Assignment
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Subjective Assignment
1.
What is a wavefront?Differentiate between a ray and a wave front.
2.
What is the geometrical shape of wavefront emitted from
(a) a source in the form of narrow slit?
(b) point source,
(c) distant light source ?
3.
Draw a diagram to show refraction of a plane wave front incident in a convex lens and hence draw the refracted wave front.
4.
Use Huygen’s principle to verify
(a)
The law Of reflection
(b)
The Snell’s laws of refraction.
5.
What is the shape of the wavefront in each of the following cases:
(a)
Light diverging from a point source.
(b)
Light emerging out of a convex lens when a point source is placed at its focus.
(c)
The portion of the wavefront of light from a distant star intercepted by the Earth.
6.
Use the Huygen’s principle to deduce directly that a point object placed in front of a plane mirror produces a virtual image whose distance from the mirror is equal to the object distance from the mirror.
7.
(a)
What is unpolarised light ?
(b)
What are polaroids. Write their uses.
8.
Unpolarized light is incident on a plane surface of glass of refractive index \displaystyle \mu at angle i. If the reflected light gets totally polarized, write the relation between the angle i and refractive index .
9.
Can we polarize (i) Heat waves (ii) x- rays (iii) Sound waves ?
10.
What happens on polarization by reflection?
11.
How does an unpolarised light get polarized when passed through a Polaroid Twopolaroids are set in crossed positions. A third Polaroid is placed between the two making an angle \displaystyle \theta with the pass axis of the first Polaroid. Write the expression for the intensity of light transmitted from the second Polaroid. In what orientations will the transmitted intensity be (i) minimum and (ii) maximum ?
12.
A beam of unpolarised light is incident on the boundary between two transparent media. If the reflected light is completely plane polarized, how is its direction related to the direction of the corresponding refracted light ? Define Brewster’s angle. Obtain the relation between this angle and the refractive index for the given pair of media.
13.
(a)
Describe briefly, with the help of suitable diagram, how the transverse nature of light can be demonstrated by the phenomenon of polarization.
(b)
When unpolarized light passes from air to a transparent medium, under what condition does the reflected light get polarized ?
14.
The velocity of a certain monochromatic light, in a given transparent medium is . What is the
(a) critical angle of incidence,
(b) Polarising angle for this medium ?
15.
Explain the following giving reason for each :
(a)
How does a polaroid work to produce a linearly polarised light from an unpolarised beam of light ?
(b)
Why is it that light waves can be polarised, but sound waves cannot be ?
(c)
Why are sun goggles made of polaroids preferred over those using coloured glasses?
(d)
In what way is plane polarized light different from an unpolarizedlight ?
(e)
What does a polaroid consist of ?
16.
A beam of unpolarized light is made to fall, from air, on its boundary with another transparent medium of refractive index . The reflected light is viewed through a rotating analyzer. Show, on a graph, the variation of intensity of light transmitted through the analyzer with the angle between the pass axis of the analyzer and the direction of the reflected beam.
17.
An unpolarised beam of light, of intensity \displaystyle {{I}_{0}} is incident on a combination of two polaroids. Find the net intensity, of the light, transmitted by the combination, when ‘pass-axis’, of the two polaroids are inclined to each other at an angle of 60º.
18.
What is the Brewster angle for air to glass transition? (Refractive index of glass = 1.5.)
19.
If the angle between the pass axis of polarizer and the analyser is 45º, write the ratio of the intensities of original and the transmitted light after passing through the analyser.