Tag: polarisation

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Questions Related to polarisation

Multiple choice polarisation of light polarisation wave optics optics physics

Two nicol prisms A and B are placed in the path of a beam of unpolarised light, so that no light emerges out of B. In between these two, a third nicol C is placed such that its principal section is at an angle of $30^0$ with that of A. The percentage of intensity of incident unpolarised light that emerges from B.

  1. $2.8$
  2. $9.4$
  3. $15.3$
  4. $10.2$
Reveal answer Fill a bubble to check yourself
B Correct answer
Multiple choice polarisation of light polarisation wave optics optics physics

Two polaroids are placed in the path of unpolarized beam of intensity ${I _0}$ such that no light is emitted from the secong polaroid. If a third polaroid whose polarization axis makes an angle $\theta $ with the polarization axis of first polaroid, is placed between these polaroids then the intensity of light emerging from the last polaroid will be

  1. $\left( {\frac{{{I _0}}}{8}} \right){\sin ^2}2\theta $
  2. $\left( {\frac{{{I _0}}}{4}} \right){\sin ^2}2\theta $
  3. $\left( {\frac{{{I _0}}}{2}} \right){\sin ^2}2\theta $
  4. ${I _0}{\cos ^4}2\theta $
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The first polarizer reduces intensity to I0/2. The second polarizer is at angle theta to the first, so intensity becomes (I0/2) * cos^2(theta). The third polarizer is at 90 degrees to the first, meaning it is at (90-theta) to the second. Intensity = (I0/2) * cos^2(theta) * cos^2(90-theta) = (I0/2) * cos^2(theta) * sin^2(theta) = (I0/2) * (sin(2*theta)/2)^2 = (I0/8) * sin^2(2*theta).

Multiple choice polarisation of light polarisation wave optics optics physics

Unpolarized light is incident on a planet sheet of water surface. The angle of incident for which the reflected and refracted rays are perpendicular to each other is $\left(\mu _{water}=\dfrac{4}{3}\right)$.

  1. $\sin^{-1}\left(\dfrac{4}{3}\right)$
  2. $\tan^{-1}\left(\dfrac{3}{4}\right)$
  3. $\tan^{-1}\left(\dfrac{4}{3}\right)$
  4. $\sin^{-1}\left(\dfrac{1}{3}\right)$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Brewster's law states that the angle of incidence for which reflected and refracted rays are perpendicular is given by tan(i) = n. Here, n = 4/3, so i = tan^-1(4/3).

Multiple choice polarisation of light polarisation wave optics optics physics

A polariser is used to :

  1. Reduced intensity of light

  2. Produced polarised light

  3. Increases intensity of light

  4. Produced unpolarised light
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A polarizer is an optical filter that lets light waves of a specific polarization pass while blocking light waves of other polarizations, effectively producing polarized light from unpolarized light.

Multiple choice polarisation of light polarisation wave optics optics physics

Which inert gas possesses the highest polarizability ? 

  1. He

  2. Ne

  3. Ar

  4. Xe
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Polarizability increases down a group in the periodic table as the atomic radius increases and the outer electrons are further from the nucleus, making them easier to displace. Xenon (Xe) is the largest noble gas listed.

Multiple choice polarisation of light polarisation wave optics optics physics

Two liner polarizers are crossed at an angle of ${ 60 }^{ \circ  }$. The fraction of intensity of light transmitted by the pair is

  1. $\dfrac { 1 }{ 4 } $
  2. $\dfrac { 1 }{ 8 } $
  3. $\dfrac { 3 }{ 8 } $
  4. $\dfrac { 1 }{ 2 } $
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Unpolarized light passing through the first polarizer has its intensity halved (I1 = I0 / 2). The second polarizer is at an angle of 60 degrees to the first, so by Malus's law, the transmitted intensity is I2 = I1 * cos^2(60) = (I0 / 2) * (1 / 4) = I0 / 8.

Multiple choice polarisation of light polarisation wave optics optics physics

A polaroid making an angle ${ 60 }^{ \circ  }$ with electric vector then intensity reduced by a factor of:-

  1. $\dfrac { 1 }{ 4 } $
  2. $\dfrac { 3}{ 4 } $
  3. $\dfrac { 1 }{ 2 } $
  4. $\dfrac { 1 }{ 3} $
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

If a polarizer makes an angle of 60 degrees with the electric vector of polarized light, the intensity is reduced by a factor of cos^2(60) = (1/2)^2 = 1/4.

Multiple choice polarisation of light polarisation wave optics optics physics

Two polaroids are placed in the path of unpolarized beam of intensity ${ I } _{ 0 }$ such that no light is emitted from the second polaroid. if  a third polaroid whose polarization axis makes an angle $\theta $ with the polarization axis of first polaroid is plcaed between these polaroids then the intensity of light emerging from the last polaroid is 

  1. $\left( \frac { { I } _{ 0 } }{ 8 } \right) { sin }^{ 2 }2\theta $
  2. $\left( \frac { { I } _{ 0 } }{ 4 } \right) { sin }^{ 2 }2\theta $
  3. $\left( \frac { { I } _{ 0 } }{ 4 } \right) { cos }^{ 4 }\theta $
  4. ${ I } _{ 0 }{ Cos }^{ 4 }\theta $
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The derivation is identical to question 527898. The intensity is (I0/8) * sin^2(2*theta).

Multiple choice polarisation of light polarisation wave optics optics physics

Two polaroids are placed in the path of unpolarized beam of intensity $I _ { 0 }$ such that no light is emitted from the second Polaroid. If a third Polaroid whose polarization axis makes an angle $\theta$ with the polarization axis of first polaroid, is placed between these polaroids then the intensity of light emerging from the last polarids will be :

  1. $\left( \dfrac { I _ { 0 } } { 8 } \right) \sin ^ { 2 } 2 \theta$
  2. $\left( \dfrac { I _ { 0 } } { 4 } \right) \sin ^ { 2 } 2 \theta$
  3. $\left( \dfrac { I _ { 0 } } { 2 } \right) \cos ^ { 4 } \theta$
  4. $I _ { 0 } \cos ^ { 4 } \theta$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This is a repeat of the previous question. The intensity is (I0/8) * sin^2(2*theta).

Multiple choice polarisation of light polarisation wave optics optics physics

Which of the following is not an anisotropic?

  1. zinc blend

  2. quartz

  3. sapphire

  4. iron oxide

  5. apatite
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Anisotropy is the property of being directionally dependent, which implies different properties in different directions.
Zinc blend (ZnS) is the only isotropic material in the list.
Quartz crystals and Saphire are birefringent, so they exhibit optical anisotropy.