EASY

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What is the difference between polarizer and analyzer?

Important Questions on Wave Optics

MEDIUM

Physics>Optics>Wave Optics>Polarization of Light

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:

EASY

Physics>Optics>Wave Optics>Polarization of Light

An unpolarised light beam of intensity

2 I_{0}

is passed through a polaroid

P

and then through another polaroid

Q

which is oriented in such a way that its passing axis makes an angle of

30 °

relative to that of

P

. The intensity of the emergent light is

EASY

Physics>Optics>Wave Optics>Polarization of Light

Unpolarised light of intensity

32 W m^{- 2}

passes through the combination of three polaroids such that the pass axis of the last polaroids is perpendicular to that of the pass axis of first polaroids. If intensity of emerging light is

3 W m^{- 2}

, then the angle between pass axis of first two polaroids is _________

°

MEDIUM

Physics>Optics>Wave Optics>Polarization of Light

Two Polaroids

P_{1}

and

P_{2}

are placed with their axis perpendicular to each other. Unpolarised light with intensity

I_{0}

is incident on

P_{1}

. A third polaroid

P_{3}

is kept in between

P_{1}

and

P_{2}

such that its axis makes an angle

45^{o}

with that of

P_{1}

. The intensity of transmitted light through

P_{2}

EASY

Physics>Optics>Wave Optics>Polarization of Light

With the help of an experiment, state how will you identify whether a given beam of light is polarised or unpolarised.

HARD

Physics>Optics>Wave Optics>Polarization of Light

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

EASY

Physics>Optics>Wave Optics>Polarization of Light

As shown in figures, three identical polaroids $P_{1}$ , $P_{2}$ and $P_{3}$ are placed one after another. The pass axis of $P_{2}$ and $P_{3}$ are inclined at angle of $60 º$ and $90 º$ with respect to axis of $P_{1}$ . The source $S$ has an intensity of $256 W m^{- 2}$ . The intensity of light at point $O$ is _____ $W m^{- 2}$ .

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EASY

Physics>Optics>Wave Optics>Polarization of Light

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}

MEDIUM

Physics>Optics>Wave Optics>Polarization of Light

How will you distinguish experimentally between ordinary light and plane-polarized light?

EASY

Physics>Optics>Wave Optics>Polarization of Light

Write any two uses of polaroids.

EASY

Physics>Optics>Wave Optics>Polarization of Light

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>Polarization of Light

In a stạck of three polarising sheets, the first and the third are crossed while the middle one has its axis at

45 °

to the axes of the other two. The fraction of intensity of an incident unpolarised beam of light that is transmitted by the stack is

MEDIUM

Physics>Optics>Wave Optics>Polarization of Light

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):

EASY

Physics>Optics>Wave Optics>Polarization of Light

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 :

HARD

Physics>Optics>Wave Optics>Polarization of Light

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 needs to be rotated further, to reduce the output intensity to zero, is

HARD

Physics>Optics>Wave Optics>Polarization of Light

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>Polarization of Light

Why polaroids are used in sunglasses?

EASY

Physics>Optics>Wave Optics>Polarization of Light

When an unpolarized light of intensity

I_{0}

is incident on a polarizing sheet, the intensity of light which does not get transmitted is

EASY

Physics>Optics>Wave Optics>Polarization of Light

A beam of light falls on a system of

4

polaroids, which are arranged in succession, such that the axis of each polaroids makes

30 °

with the axis of the preceding one. The fraction of the intensity of the incident light that passes through the system is

EASY

Physics>Optics>Wave Optics>Polarization of Light

How does an unpolarised light incident on a polaroid get polarised ? Describe briefly, with the help of a necessary diagram, the polarisation of light by reflection from a transparent medium.

What is the difference between polarizer and analyzer?

Important Questions on Wave Optics

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