Tag: physics

Questions Related to physics

Optically active substances are those which

polarisation of light polarisation wave optics optics physics

  1. produce polarized light

  2. rotate the plane of polarization of the polarized light.

  3. produce double refraction

  4. convert a plane polarized light into circularly polarized light.

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Correct Option: B
Explanation:

Optically active substance by definition are substances which can rotate the plane of polarization of polarized light.


Answer. B) rotate the plane of polarization of polarized light.

If for a calcite crystal, $\displaystyle\mu _0$ and $\displaystyle\mu _e$ are the refractive indices of the crystal for O-ray and E-ray repectively, then along the optic axis of the crystal

polarisation of light polarisation wave optics optics physics

  1. $\displaystyle\mu _0$ = $\displaystyle\mu _e$

  2. $\displaystyle\mu _0$ > $\displaystyle\mu _e$

  3. $\displaystyle\mu _0$ < $\displaystyle\mu _e$

  4. None of these

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Correct Option: A
Explanation:

In calcite crystal, only along the optical axis, the refractive indices of the crystal are equal for O-ray and E-ray

Optically active substances are those substances which 

polarisation of light polarisation wave optics optics physics

  1. produces polarised light

  2. produces double refraction

  3. rotate the plane of polarisation of polarised light

  4. converts a plane polarised light into circularly polarised light

Show answer
Correct Option: C
Explanation:

By definition, optically active substances are those which can rotate the plane of polarisation of polarised light.

Polaroid glass is used in sun glasses because

polarisation of light polarisation wave optics optics physics

  1. it reduces the light intensity to half on account of polarisation

  2. it is fashoinable

  3. it has good colour

  4. it is cheaper

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Correct Option: A
Explanation:

Polaroid glass cut glare and haze by reducing the light intensity to half on account of polarisation, so that eyes are more comfortable and viewer can see better, therefore they are used in sun glasses.

A nicol prism is based on action of

polarisation of light polarisation wave optics optics physics

  1. refraction

  2. double refraction

  3. dichroism

  4. both (b) and (c)

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Correct Option: D
Explanation:

When a ray of light enters nicol prism, it splits into two plane polarised light in mutually perpendicular direction. One of this light undergoes total reflection and absorption whereas other comes out as a plane polarised light.

If a polaroid is kept in the path of an uniformly unpolarised light, the intensity of the transmitted light to the intensity of the light when the polaroid was not kept in its path is.

polarisation of light polarisation wave optics optics physics

  1. 1

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

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

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

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Correct Option: B
Explanation:
The component of the electric vector of all the electric vectors of unpolarised light in one direction only = $\dfrac {E _0}{\sqrt {2}} $
And, $I \propto E^2 \Rightarrow I = \dfrac {I _0}2 $

A Nicol prism can be used.

polarisation of light polarisation wave optics optics physics

  1. For producing and analysing polarised light

  2. Only to analyse polarized light

  3. Only to produce polarized light

  4. None of the above

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Correct Option: A
Explanation:

A Nicol prism is use to produce and analyse the polarised light.

What is used to measure doppler line broadening.

polarisation of light polarisation wave optics optics physics

  1. Polaroid

  2. Diffration grating

  3. Herapathite

  4. Plasma

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Correct Option: D

The angle of incidence at which reflected light is totally polarized form aim is :

polarisation of light polarisation wave optics optics physics

  1. $\sin ^ { - 1 } ( n )$

  2. $\sin ^ { - 1 } \left( \frac { 1 } { n } \right)$

  3. $\tan ^ { - 1 } \left( \frac { 1 } { n } \right)$

  4. $\tan ^ { - 1 } ( n )$

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Correct Option: D

A person takes hot tea by pouring it into the saucer (plate) when one is in a hurry because he knows that

physics thermal physics heat and heat transfer transfer of heat fundamentals of heat transfer

  1. The latent heat of steam is high and the tea will become cold quickly

  2. The evaporation increases with the increase in surface area and cooling of tea is faster

  3. Part of heat will be absorbed by the saucer (plate) and the tea will become cold quickly

  4. The high specific heat of water makes the tea cold quickly

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Correct Option: B