Column I Column II ( i ) Interference ( P ) Coherent sources ( ii ) Brewster's Law ( Q ) μ = 1 sinC ( iii ) Malus Law ( R ) μ = tanθ p ( iv ) Total Internal reflection ( S ) I = I 0 cos 2 θ

i → P , ii → R , iii → S , iv → Q

i → Q , ii → S , iii → R , iv → P

i → P , ii → S , iii → R , iv → Q

i → R , ii → Q , iii → S , iv → P

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When a Polaroid sheet is rotated between two crossed polaroids, the intensity of the transmitted will be maximum, when angle $θ$ between pass axes is

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Important Questions on Wave Optics

MEDIUM

Physics>Optics>Wave Optics>Polarisation

The Brewsters angle

i_{b}

for an interface should be

EASY

Physics>Optics>Wave Optics>Polarisation

Unpolarized light of intensity

I

passes through an ideal polariser

A

. Another identical polariser

B

is placed behind

A

. The intensity of light beyond B is found to be

\frac{I}{2}

. Now another identical polariser

C

is placed between

A

and

B

. The intensity beyond B is now found to be

\frac{I}{8}

. The angle between polariser

A

and

C

EASY

Physics>Optics>Wave Optics>Polarisation

A transparent medium shows relation $i$ and $r$ as shown. If the speed of light in vacuum is $c,$ the Brewster angle for the medium is

Question Image

HARD

Physics>Optics>Wave Optics>Polarisation

Unpolarised red light is incident on the surface of a lake at incident angle $θ_{R}$ . An observer seeing the light reflected from the water surface through a polariser notices that on rotating the polariser, the intensity of light drops to zero at a certain orientation. The red light is replaced by unpolarised blue light. The observer sees the same effect with reflected blue light at incident angle $θ_{B}$ .

Then,

MEDIUM

Physics>Optics>Wave Optics>Polarisation

Two circular linear polarisers are placed coaxially. The transmission axis of the first polariser is

30 °

from the vertical while the second one is at

60 °

, both in the clockwise sense. If an unpolarised beam of light of intensity,

I = 20 W m^{- 2}

is incident on this pair of polarisers, then the intensities

I_{1}

and

I_{2}

transmitted by the first and the second polarisers, respectively, will be close to,

MEDIUM

Physics>Optics>Wave Optics>Polarisation

A ray of unpolarised light is incident on the glass surface of refractive index

1.73

at polarizing angle. The angle of refraction will be [Take

\tan 60 ° = 1.73

]

MEDIUM

Physics>Optics>Wave Optics>Polarisation

A system of three polarizers

P_{1}, P_{2}, P_{3}

is set up such that the pass axis of

P_{3}

is crossed with respect to that of

P_{1}

. The pass axis of

P_{2}

is inclined at

60^{o}

to the pass axis of

P_{3} .

When a beam of unpolarized light of intensity

I_{o}

is incident on

P_{1},

the intensity of light transmitted by the three polarizers is

I

. The ratio

(I_{o} / I)

equals (nearly):

MEDIUM

Physics>Optics>Wave Optics>Polarisation

A ray of light travelling in impure water is incident on a glass plate immersed in it. When the angle of incidence is

51 °,

the reflected ray is totally plane polarized. Given that refractive index of impure water is

1.4 .

The refractive index of glass should be _____

(\tan 51 ° = 1.235)

MEDIUM

Physics>Optics>Wave Optics>Polarisation

θ

is the polarising angle for two optical media whose critical angles are

C_{1}

and

C_{2}

, then the correct relation is

HARD

Physics>Optics>Wave Optics>Polarisation

Unpolarized light of intensity

I

is incident on a system of two polarizers,

A

followed by

B

. The intensity of emergent light is

\frac{I}{2}

. If a third the polarizer

C

is placed between

A

and

B

the intensity of emergent light is reduced to

\frac{I}{3}

. The angle between the polarizers

A

and

C

θ

, then

HARD

Physics>Optics>Wave Optics>Polarisation

A camera filled with a polarizer is placed on a mountain, in a manner to record only the reflected image of the sun from the surface of a sea as shown in the figure. If the sun rises at $6.00 AM$ and sets at $6.00 PM$ during the summer, then at what time in the afternoon will the recorded image have the lowest intensity, assuming there are no clouds and intensity of the sun at the sea surface is constant throughout the day? (Refractive index of water $= 1.33$ )

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EASY

Physics>Optics>Wave Optics>Polarisation

Unpolarised light is incident from air on plane surface of a material of refractive index

μ

. At a particular angle of incident

i

it is found that the reflected and refracted rays are perpendicular to each other. Which of the following options is correct for this situation?

EASY

Physics>Optics>Wave Optics>Polarisation

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.

EASY

Physics>Optics>Wave Optics>Polarisation

Three polaroid sheets

P_{1}, P_{2}

and

P_{3}

are kept parallel to each other such that the angle between pass axes of

P_{1}

and

P_{2}

45 °

and that between

P_{2}

and

P_{3}

45 °

. If unpolarised beam of light of intensity

128 W m^{- 2}

is incident on

P_{1}

. What is the intensity of light coming out of

P_{3}

HARD

Physics>Optics>Wave Optics>Polarisation

	Column I		Column II
$(i)$	Interference	$(P)$	Coherent sources
$(ii)$	Brewster's Law	$(Q)$	$μ = \frac{1}{sinC}$
$(iii)$	Malus Law	$(R)$	$μ = {tanθ}_{p}$
$(iv)$	Total Internal reflection	$(S)$	$I = I_{0} \cos^{2} θ$

HARD

Physics>Optics>Wave Optics>Polarisation

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

HARD

Physics>Optics>Wave Optics>Polarisation

Three circularly shaped linear polarisers are placed coaxially. The transmission axis of the first polariser is at

30 °

, the second one is at

60 °

and the third at

90 °

to the vertical all in the clockwise sense. Each polariser additionally absorbs

10 %

of the light. If a vertically polarised beam of light of intensity

I = 100 W m^{- 2}

is incident on this assembly of polarisers, then the final intensity of the transmitted light will be close to:

EASY

Physics>Optics>Wave Optics>Polarisation

The polarising angle for transparent medium is

θ

v

is the speed of light in that medium. Then the relation between

θ

and

v

is (

c

= velocity of light in air)

EASY

Physics>Optics>Wave Optics>Polarisation

Two beams, A and B of plane polarized light with mutually perpendicular planes of polarization are seen through a polaroid. From the position when the beam A has maximum intensity (and beam B has zero intensity), a rotation of polaroid through 30^o makes the two beams appear equally bright. If the initial intensities of the two beams are I_A and I_B respectively, then

\frac{I_{A}}{I_{B}}

equals :

MEDIUM

Physics>Optics>Wave Optics>Polarisation

A beam of unpolarised light of intensity

I_{0}

is passed through a polaroid

A

and then through another polaroid

B

which is oriented so that its principle plane makes an angle of

45^{o}

relative to that of

A

. The intensity of the emergent light is:

When a Polaroid sheet is rotated between two crossed polaroids, the intensity of the transmitted will be maximum, when angle θ between pass axes is

Important Questions on Wave Optics

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When a Polaroid sheet is rotated between two crossed polaroids, the intensity of the transmitted will be maximum, when angle $θ$ between pass axes is