Tag: physics

Questions Related to physics

Bartholinus discovered :

polarisation of light polarisation wave optics optics physics

  1. Interference by splitting the wave front

  2. Polarisation by reflection

  3. Polarisation by refraction

  4. Polarisation by double refraction

Show answer
Correct Option: D
Explanation:

In 1669, another Danish scientist, Erasmus Bartholinus discovered the polarization of light by double refraction in Iceland spar (calcite).

Choose the correct statements among the following given options.

polarisation of light polarisation wave optics optics physics

  1. Brewster's angle is independent of wavelength of light.

  2. Brewster's angle is independent of the nature of reflecting surface.

  3. Brewster's angle is different for different wavelengths.

  4. Brewsters angle depends on wavelength but not on the nature of reflecting surface.

Show answer
Correct Option: C
Explanation:

Brewster's angle is an angle of incidence at which light with a particular polarization is perfectly transmitted through a transparent dielectric surface,
with no reflection.
$\theta _{B}=tan^{-1}(\dfrac{n _{2}}{n _{1}})$
$n _{2}$ refractive index of final medium
$n _{1}$ refractive index of initial medium
As different wavelength have different refractive indices the brewster angle is also different.

Pile of plates can be used to produce completely polarised light due to :

polarisation of light polarisation wave optics optics physics

  1. Reflection

  2. Refraction

  3. Double refraction

  4. A and B

Show answer
Correct Option: B
Explanation:

pile of plates is used to produce plane polarized light by refraction.
By refraction through multiple plates vibrations in the plane of incidence are transmitted.
Thus we obtain a polarized light.

At the polarising angle $(\theta _{B})$, angle of refraction is given by : 

polarisation of light polarisation wave optics optics physics

  1. $90^{\circ}$

  2. $90^o+\theta _{B}$

  3. $90^o-\theta _{B}$

  4. $\dfrac{90^o}{\theta _B }$

Show answer
Correct Option: C
Explanation:

At polarizing angle $\theta _{B}$
$\dfrac{sin \theta _{B}}{cos \theta _{B}}=\dfrac{sin \theta _{B}}{sin \gamma }$
we get $sin \gamma =cos \theta _{B}$
$sin \gamma =sin(90-\theta _{B})$
Thus $\gamma =90-\theta _{B}$

The angle of incidence at which reflected light is totally polarised for reflection from air to glass (refractive index n) is :

polarisation of light polarisation wave optics optics physics

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

  2. $sin^{-1}(1/n)$

  3. $ tan^{-1}(n)$

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

Show answer
Correct Option: C
Explanation:

The refractive index of glass is n
If the light is incident on the surface with an angle of incidence i given by tan i $=\mu $ using the Brewster's law the reflected light is completely polarized.
Here tan i $=n$
i$=tan^{-1}(n)$

A light ray is incident on a transparent medium of $\mu =$ 1.732 at the polarizing angle. The angle of refraction is :

polarisation of light polarisation wave optics optics physics

  1. 60$^{\circ}$

  2. 30$^{\circ}$

  3. 45$^{\circ}$

  4. 90$^{\circ}$

Show answer
Correct Option: B
Explanation:

Angle of incidence $=$ polarising angle
$tan i = \mu $
$tan i = 1.732$
$i = 60^{0}$
From snell's law
$\dfrac{sin i}{sin \gamma }=\mu $
$sin \gamma =\dfrac{sin 60^{0}}{1.732}$
$\gamma =30^{0}$

The critical angle for total internal reflection for a substance is $45^{\circ}$. The polarizing angle for this substance is ($\tan 54^{\circ}44'=\sqrt{2}$) :

polarisation of light polarisation wave optics optics physics

  1. $46^{\circ}16'$

  2. $54^{\circ}44'$

  3. $46^{\circ}44'$

  4. $54^{\circ}16'$

Show answer
Correct Option: B
Explanation:

If polarizing angle is $\theta $
Then tan $\theta =\dfrac{1}{sin c}$
$tan \theta =\dfrac{1}{sin 45}=\sqrt{2}$
$\theta =54^{0}{44}'$

ASSERTION (A):Hyugens' theory failed to explain polarization
REASON (R): According to Hyugens' theory light is longitudinal wave

polarisation of light polarisation wave optics optics physics

  1. A is correct, R is correct and it is the correct explanation

  2. A is correct, R is correct but it is not a correct explanation

  3. A is correct, R is wrong

  4. A is wrong , R is correct

Show answer
Correct Option: A
Explanation:

Huygen's theory failed to explain polarisation because according to the Huygen's theory light is a longitudinal waves and longitudinal wave does not shows polarisation.

According to Maxwell , most of the optical properties of light depend on

polarisation of light polarisation wave optics optics physics

  1. Magnetic vector

  2. Electric vector

  3. Both Electric and Magnetic vectors

  4. Can not be decided

Show answer
Correct Option: B
Explanation:

The experiments on stationary light waves establish that most of the optical properties of light depends on the electric vector, which is also known as light vector.

Identify which of the following should be used for polarised light waves?
I. Sunglasses
II. Remove ultraviolet light
III. Reveal stress patterns

polarisation of light polarisation wave optics optics physics

  1. I only

  2. II only

  3. I and III only

  4. II and III only

  5. I, II, and III

Show answer
Correct Option: C
Explanation:

Polarizers are used in industry to reveal stress patterns in machinery and tools. Sunglasses are used to protect the eyes by polarizing the light to reduce glare using the tailor-made material of the glasses.