Tag: polarisation

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Questions Related to polarisation

Multiple choice polarisation of light polarisation wave optics optics physics

When unpolarized light beams are incidents in the air into glass ($n=1.5$ at polarising angle)

  1. reflected beams is $100$ polarised

  2. reflect and refracted beams are partially polarised

  3. the reason for (a) is that almost all the light is reflected

  4. all the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

When unpolarized light is incident at Brewster angle from one medium to another, the light that is reflected from the surface is perfectly polarized

Multiple choice polarisation of light polarisation wave optics optics physics

Dichorism means

  1. selective absorption of unpolarised light.

  2. selective absorption of dispersed light.

  3. selective absorption of scattered light.

  4. selective absorption of one of the polarised component.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Dichromism is the selective absorption of one orthogonal polarization component of an incident beam over the other. this phenomenon is due to anisotropy of the material, with one polarization component experiencing preferential absorption.

Multiple choice polarisation of light polarisation wave optics optics physics

From Brewster's law, it follows that the angle of polarization depends upon

  1. the wavelength of light

  2. orientation of the plane of polarization

  3. orientation of the plane of vibration

  4. none of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$\theta _B=tan^{-1}\dfrac{n _2}{n _1}$

Since the refractive index for a given medium changes depending on the wavelength of light, Brewster's angle will also vary with wavelength.

Multiple choice polarisation of light polarisation wave optics optics physics

When unpolarized light is incidents on a plane glass plate at Brewster's angle, then which of the following statements is correct?

  1. Reflect and refracted rays are completely polarized with their planes of polarization parallel to each other.

  2. Reflect and refracted rays are completely polarized with their planes of polarization perpendicular to each other.

  3. Reflected light is the plane polarized but transmitted light is partially polarized.

  4. Reflected light is partially polarized but refracted light is plane polarized.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Reflect and refracted rays are completely polarized with their planes of polarization perpendicular to each other.
option $B$ is correct 

Multiple choice polarisation of light polarisation wave optics optics physics

The transverse nature of light waves is verified by

  1. reflection of light

  2. polarisation of light

  3. refraction of light

  4. interference of light
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Phenomenon of polarisation helps in establishing the fact that light waves are transverse in nature, otherwise it was believed that they are longitudinal in nature like sound waves.

Multiple choice polarisation of light polarisation wave optics optics physics

$\lambda _a$ and $\lambda _m$ are the wavelengths of the beam of light in air and in medium, respectively. If $\theta$ is the polarizing angle then, the correct relationship between $\lambda _a, \lambda _m$ and $\theta$ is 

  1. $\lambda _a=\lambda _m\tan 2=\theta$
  2. $\lambda _m=\lambda _a\tan ^2=\theta$
  3. $\lambda _a=\lambda _m\cot=\theta$
  4. $\lambda _m=\lambda _a\cot=\theta$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Brewster's angle or polarizing angle is given by $\tan\theta=\dfrac{n _{medium}}{n _{air}}=\dfrac{\lambda _a}{\lambda _m}$

Thus $\lambda _m=\lambda _a\cot\theta$

Multiple choice polarisation of light polarisation wave optics optics physics

Which of these waves can be polarised ?

  1. Sound waves

  2. Longitudinal waves on a string

  3. Transverse waves on a string

  4. Light waves
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
  • Only transverse waves can be polarised. Longitudinal waves (sound waves in air) cannot be polarised. The reason that only transverse wave can be polarised is that their vibrations can  be potentially occur in all directions perpendicular to the direction of travel.
  • Polarisation of "light wave" is possible only because they can oscillate in more than one orientation because they are transverse in Nature.
  • It has no dependence  on wavelength and frequencies
  • Hence option D is the right answer
Multiple choice polarisation of light polarisation wave optics optics physics

When unpolarised light is incident on a plane glass plate at Brewster's angle, then which of the following statements is correct?

  1. Reflected and refracted rays are completely polarised with their planes of polarisation parallel to each other

  2. Reflected and refracted rays are completely polarised with their planes of polarisation perpendicular to each other

  3. Reflected light is plane polarised but transmitted light is partially polarised

  4. Reflected light is partially polarised but refracted light is plane polarised
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

At Brewster angle, only the reflected light is completely plane polarised, but the transmitted (refracted) light is partially polarised.

Multiple choice polarisation of light polarisation wave optics optics physics

If the light is polarised by reflection, then the angle between reflected and refracted light is

  1. 180$^o$
  2. 90$^o$
  3. 45$^o$
  4. 36$^o$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

When the reflected light is completely polarised, then the angle between reflected and refracted ray are $ { 90 }^{ o }$

Multiple choice polarisation of light polarisation wave optics optics physics

A ray of light strikes a glass plate at an angle of 60$^{o}$. If the reflected and refracted rays are perpendicular to each other, the index of refraction of glass is

  1. $\displaystyle\frac{1}{2}$
  2. $\displaystyle\sqrt{\frac{3}{2}}$
  3. $\displaystyle\frac{3}{2}$

  4. 1.732
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

As reflected and refracted rays are perpendicular to each other, therefore, i$ _p$ = i = 60$^{o}$, where i$ _p$ is called angle of polarisation.
$\displaystyle\mu = tan i _{p} = tan 60^{o} = \sqrt{3}$ = 1.732.