An electromagnetic wave in vacuum has the electric and magnetic fields E → and B → which are always perpendicular to each other. The direction of polarizations is given by X → and wave propagation by K → then

X → ‖ E → and K → ‖ E → × B → .

X → ‖ B → and K → ‖ E → × B → .

X → ‖ E → and K → ‖ B → × E → .

X → ‖ B → and K → ‖ B → × E → .

An electromagnetic wave in vacuum has the electric and magnetic fields E → and B → which are always perpendicular to each other. The direction of polarizations is given by X → and wave propagation by K → then

X → ‖ E → and K → ‖ E → × B → .

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An electromagnetic wave in vacuum has the electric and magnetic fields $\vec{E}$ and $\vec{B}$ which are always perpendicular to each other. The direction of polarizations is given by $\vec{X}$ and wave propagation by $\vec{K}$ then

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Important Questions on Wave Optics

HARD

Physics>Optics>Wave Optics>Polarisation

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

MEDIUM

Physics>Optics>Wave Optics>Polarisation

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}

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

The Brewsters angle

i_{b}

for an interface should be

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:

MEDIUM

Physics>Optics>Wave Optics>Polarisation

A beam of plane polarized light of large cross-sectional area and uniform intensity of

3 .3 W m^{- 2}

falls normally on a polarizer (cross-sectional area

3 \times 10^{- 4} m^{2}

), which rotates about its axis with an angular speed of

31 .4 rad s^{- 1}

. The energy of light passing through the polarizer per revolution, is close to:

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

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,

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

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

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}

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 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

]

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

EASY

Physics>Optics>Wave Optics>Polarisation

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>Polarisation

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>Polarisation

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

EASY

Physics>Optics>Wave Optics>Polarisation

When the angle of incidence on a transparent material is

60 °

, the reflected light is completely polarised. The velocity of refracted ray inside the material is

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

Unpolarized light of intensity

I_{0}

is incident on surface of a block of glass at Brewster's angle. In that case, which one of the following statements is true?

An electromagnetic wave in vacuum has the electric and magnetic fields E→ and B→ which are always perpendicular to each other. The direction of polarizations is given by X→ and wave propagation by K→ then

Important Questions on Wave Optics

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An electromagnetic wave in vacuum has the electric and magnetic fields $\vec{E}$ and $\vec{B}$ which are always perpendicular to each other. The direction of polarizations is given by $\vec{X}$ and wave propagation by $\vec{K}$ then