Tag: optics

Questions Related to optics

The tourmaline crystal

polarisation of light polarisation wave optics optics physics

  1. Absorbs ordinary light and transmits extra ordinary

  2. Absorbs extra ordinary light and transmits ordinary light

  3. Both absorbs ordinary and extra ordinary light

  4. Both transmits ordinary light and extra ordinary light

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Correct Option: D
Explanation:

Some transparent crystals, such as tourmaline and calcite, have the property that when one views an object through them one sees two images of the object. If one passes a narrow beam of light through them, the refracted beam is split into two parts which travel through the crystal and emerge as two separate beams. One of the beams obeys the ordinary laws of refraction and is called the ordinary ray. The other beam is called the extraordinary ray. The extraordinary ray does not always lie in the plane of incidence. Its speed, and consequently its index of refraction, depends on its direction of propagation through the crystal.

Since the speed of the emerging rays and angle are different, the emergent rays are circularly or optically polarized.
Hence both ordinary and extraordinary light are transmitted.
The correct answer is option D.

What happens to electric field component when unpolarized light is incident on surface such that reflected and refracted light are at right angles?

polarisation of light polarisation wave optics optics physics

  1. Parallel component remains in reflected light

  2. Prependicular component remains in reflected
    light

  3. It will remain unpolarized

  4. Partially polarised reflected light.

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Correct Option: B

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.

polarisation of light polarisation wave optics optics physics

  1. $2.8$

  2. $9.4$

  3. $15.3$

  4. $10.2$

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Correct Option: C

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

polarisation of light polarisation wave optics optics physics

  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 $

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Correct Option: A

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 $\left(\mu _{water}=\dfrac{4}{3}\right)$.

polarisation of light polarisation wave optics optics physics

  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. $\sin^{-1}\left(\dfrac{1}{3}\right)$

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Correct Option: C

A polariser is used to :

polarisation of light polarisation wave optics optics physics

  1. Reduced intensity of light

  2. Produced polarised light

  3. Increases intensity of light

  4. Produced unpolarised light

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Correct Option: B

Which inert gas possesses the highest polarizability ? 

polarisation of light polarisation wave optics optics physics

  1. He

  2. Ne

  3. Ar

  4. Xe

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Correct Option: D

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

polarisation of light polarisation wave optics optics physics

  1. $\dfrac { 1 }{ 4 } $

  2. $\dfrac { 1 }{ 8 } $

  3. $\dfrac { 3 }{ 8 } $

  4. $\dfrac { 1 }{ 2 } $

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Correct Option: A

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

polarisation of light polarisation wave optics optics physics

  1. $\dfrac { 1 }{ 4 } $

  2. $\dfrac { 3}{ 4 } $

  3. $\dfrac { 1 }{ 2 } $

  4. $\dfrac { 1 }{ 3} $

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Correct Option: A

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 

polarisation of light polarisation wave optics optics physics

  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 $

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Correct Option: A