Tag: polarisation

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Questions Related to polarisation

Multiple choice polarisation of light polarisation wave optics optics physics

Polarising angle for water is ${ 53 }^{ o }{ 4 }^{ \prime  }$. If light is incident at this angle on water and reflected, the angle of refraction is :

  1. ${ 126 }^{ o }{ 56 }^{ \prime }$
  2. ${ 36 }^{ o }{ 56 }^{ \prime }$
  3. ${ 30 }^{ o }$
  4. ${ 36 }^{ o }{ 20 }^{ \prime }$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Polarising angle for water, $i _p = 53^o4'$

Angle of refraction, $r = 90^o - i _p$
$\Rightarrow $  $r = 90^o - 53^o 4'$
$\Rightarrow r = 89^o 60' - 53^o 4'  = 36^o 56'$

Multiple choice polarisation of light polarisation wave optics optics physics

A plane polarized light passed through successive polarizers which are rotated by $30^{\circ}$ with respect to each other in the clockwise direction. Neglecting absorption by the polarizers and given that the first polarizer's axis is parallel to the plane of polarization of the incident light, the intensity of light at the exit of the fifth polarizer is closest to.

  1. Same as that of the incident light
  2. $17.5$% of the incident light
  3. $30$% of the incident light

  4. Zero
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

$I=I _o (cos^2\phi)^4$

$I=I _o (cos^230)^4$
$I=30$% of $I _o$

Multiple choice polarisation of light polarisation wave optics optics physics

The refractive index of the medium, for the polarising angle $60^o$ is?

  1. $1.732$
  2. $1.414$
  3. $1.5$
  4. $1.468$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Relation between refractive index of medium and polarising angle is given by
$n = \tan i _p$
Given :  Polarising angle  $i _p = 60^o$
So, refractive inedx  $n = \tan (60^o) = 1.732$

Multiple choice polarisation of light polarisation wave optics optics physics

When the separation between the central maxima of the two objects is greater than a separation between central maximum of a first object and the first minima of the first object, then objects are said to be

  1. just resolved

  2. well resolved

  3. not resolved

  4. none of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

well resolved (definition of qualia)

Multiple choice polarisation of light polarisation wave optics optics physics

The diameter of an objective of a telescope, which can just resolve two stars situated at an angular displacement of ${10^{ - 4}}$ degree, should be $\left( {\lambda  = 5000\,{A^0}} \right)$ 

  1. 35 mm

  2. 35 cm

  3. 35 m

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$\Delta \theta  = \left( {\dfrac{{1.22\lambda }}{d}} \right)$
$d = \left( {\dfrac{{1.22 \times \lambda }}{{\Delta \theta }}} \right)$
$ \Rightarrow \,\,{10^{ - 4}}\, \to \,\dfrac{\lambda }{{180}} \times {10^{ - 4}}$
$ = 1.74 \times {10^{ - 6}}\,rad.$
$d = \left( {\dfrac{{1.22 \times 5000 \times {{10}^{ - 10}}}}{{1.74 \times {{10}^{ - 6}}}}} \right)$
$ = 0.35\,m\,\,or\,\,35\,cm$

Multiple choice polarisation of light polarisation wave optics optics physics

A beam of natural light falls on a system of 5 polaroids, which are arranged in succession such that the pass axis of each Polaroid is turned through $60^0$ with respect to the preceding one. The fraction of the incident light intensity that passes through the system is

  1. $\dfrac{1}{64}$
  2. $\dfrac{1}{32}$
  3. $\dfrac{1}{256}$
  4. $\dfrac{1}{128}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Multiple choice polarisation of light polarisation wave optics optics physics

What proves that light is a transverse wave?

  1. Polarization

  2. Reflection

  3. Refraction

  4. Interference
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A transverse wave is a wave that oscillates perpendicular to its direction of propagation.  Polarization of light proved that light is a transverse wave.

Multiple choice polarisation of light polarisation wave optics optics physics

The helical structures of nucleic acids can be studied by using :

  1. Interference phenomenon

  2. Diffraction pattern

  3. Polarised light

  4. Photoelectric effect
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Polarised light is used to studied helical structures of nucleic acids using different methods such as optical rotatory dispersion. In this method due to refractive indices of the medium for left and right circularly polarised light reflects the structural details of such molecular complexes.

Multiple choice polarisation of light polarisation wave optics optics physics

In the light emerging from calcite crystal :

  1. Both O-ray and E-ray are partially polarised

  2. Both O-ray and E-ray are completely polarised

  3. O-ray is partially polarised and E-ray is completely polarised.

  4. O-ray is completely polarised and E-ray is partially polarised.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Because of birefringence the ordinary and extra ordinary ray are completely polarized.

Multiple choice polarisation of light polarisation wave optics optics physics

In double refraction :

  1. the velocity of the E-ray varies with direction

  2. e-ray does not obey Snell's law
  3. $\mu $ of E-ray is constant

  4. both A and B
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Because the speed of light waves in a medium is equal to their speed in a vacuum divided by the index of refraction for that wavelength, an extra ordinary ray can be either faster or slower than an ordinary ray. The extra ordinary ray does not obey snell's law. It is because refractive index of the e-ray varies according to the direction taken because it has components that are both parallel and perpendicular to the crystal's optic axis.