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Multiple choice polarisation of light polarisation wave optics optics physics

Which of the following cannot be polarised

  1. Radio waves

  2. UV rays

  3. IR rays

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

Polarization is a property of transverse waves. Ultrasonic waves are longitudinal waves and cannot be polarized.

Multiple choice polarisation of light polarisation wave optics optics physics

A beam of light strikes a piece of glass at an angle of incidence of $60 ^ { \circ }$ and the reflected beam is completely Plane polarised. Find the refractive index of this glass

  1. $\sqrt { 2 }$

  2. $\sqrt { 3 / 2 }$

  3. $\sqrt { 3 }$

  4. $\cfrac { 3 } { 2 }$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Refractive index mu = tan(i_p) = tan(60) = sqrt(3).

Multiple choice polarisation of light polarisation wave optics optics physics

If the polarizing angle for a given medium is $60^{\circ}$, then the refractive index of the medium is 

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

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

  3. 2

  4. $\sqrt{3}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Refractive index mu = tan(i_p) = tan(60) = sqrt(3).

Multiple choice polarisation of light polarisation wave optics optics physics

A polarizer and an analyzer are arranged with their optic axes parallel to each other Symmetric light first passes through the polarizer and then the analyzer and the intensity of the light emerging is 'I'. If the analyzer is turned through $30^o$, the percent changes in the intensity is

  1. $75\%$

  2. $50\%$

  3. $25\%$

  4. $40\%$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Initial intensity I = I_0. After turning 30 degrees, I' = I_0 * cos^2(30) = I_0 * 3/4. The change is I_0 - 0.75I_0 = 0.25I_0, which is 25%.

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