Tag: optics

Quizzes (33) Questions (198)

Questions Related to optics

Multiple choice polarisation of light polarisation wave optics optics physics

When sun light is incident on water at an angle of $ 53^o $ the reflected light is found to be completely plane-polarised. Determine : (i) angle of refraction of light,
(ii) refractive index of water.

  1. (i) $ 31^o $
    (ii) $ 1.427 $
  2. (i) $ 30^o $
    (ii) $ 2.327 $
  3. (i) $ 27^o $
    (ii) $ 1.327 $
  4. (i) $ 37^o $
    (ii) $ 1.327 $
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Given i_p = 53 degrees. Angle of refraction r = 90 - 53 = 37 degrees. Refractive index mu = tan(53) = 1.327.

Multiple choice polarisation of light polarisation wave optics optics physics

The angle between polariser and analyser is $30 ^ { \circ }$  The ratio of intensity of incident light and transmitted by the analyser is

  1. 3:4

  2. 4:3
  3. $\sqrt { 3 } : 2$
  4. $2 : \sqrt { 3 }$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Given,
$\theta=30^0$
By using malus law,
$I=I _0cos^2\theta$
$\dfrac{I}{I _0}=(cos30)^2$
$\dfrac{I}{I _0}=(\dfrac{\sqrt{3}}{2})^2=\dfrac{3}{4}$
ratio, $I:I _0=3:4$
The correct option is A.
Multiple choice polarisation of light polarisation wave optics optics physics

The angle of incidence of light is equal to Brewster's angle, then 
A) Reflected ray is perpendicular to refracted ray
B) Reflected ray is parallel to refracted ray
C) Reflected light is polarized having its electric vector in the plane of incidence 
D) Refracted light is polarized.

  1. (A) and (D) are true

  2. (A) and (B) are true

  3. (A) and (C) are true

  4. (B) and (C) are true
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

At Brewster's angle, the reflected and refracted rays are perpendicular (A). The reflected light is polarized perpendicular to the plane of incidence (C is incorrect). The refracted light is partially polarized (D is correct).

Multiple choice polarisation of light polarisation wave optics optics physics

A beam of unpolarised light of intensity $I _{0}$ is passed through a polaroid $A$ and then through another polaroid $B$ which is oriented so that its principal plane makes an angle of $45^{\circ}$ relative to that of $A$. The intensity of the emergent light is

  1. $I _{0}$
  2. $I _{0}/2$
  3. $I _{0}/4$
  4. $I _{0}/8$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

When unpolarized light of intensity I0 passes through the first polaroid A, its intensity becomes I1 = I0 / 2. When it passes through the second polaroid B at an angle of 45 degrees, Malus's law applies: I2 = I1 * cos^2(45) = (I0 / 2) * (1 / 2) = I0 / 4.

Multiple choice polarisation of light polarisation wave optics optics physics

Polarizing angle for water is $53^o4'$. If light is incident at this angle on the surface of water and reflected the angle of refraction is:

  1. $53^o4'$
  2. $126^o56'$
  3. $36^o56'$
  4. $30^o4'$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

At the polarizing angle, i_p + r = 90 degrees. r = 90 - 53 degrees 4 minutes = 36 degrees 56 minutes.

Multiple choice polarisation of light polarisation wave optics optics physics

Through which character we can distnguish the light waves from sound waves.

  1. Interference

  2. Refraction

  3. Polarisation

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

Both light and sound waves exhibit interference, refraction, and reflection because these are general wave properties. However, light is a transverse electromagnetic wave and can be polarized, whereas sound is a longitudinal pressure wave and cannot be polarized.

Multiple choice polarisation of light polarisation wave optics optics physics

In the propagation of light waves, the angle between the direction of vibration and plane of polarization is :

  1. $0^{ \circ }$
  2. $90^{ \circ }$
  3. $45^{ \circ }$
  4. $80^{ \circ }$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In transverse wave propagation, the direction of vibration of the electric field vector is perpendicular to the direction of wave travel, while the plane of polarization contains the direction of propagation and the vibration vector. Thus, the angle between the direction of vibration and the plane of polarization is 90 degrees.

Multiple choice polarisation of light polarisation wave optics optics physics

A stretched string is 1 m long. Its mass per unit length is 0.5 g/m. It is stretched with a force of 20 N. It plucked at a distance of 25 cm from one end. The frequency of note emitted by it will be:

  1. $400 Hz$
  2. $300 Hz$
  3. $200 Hz$
  4. $100 Hz$
Reveal answer Fill a bubble to check yourself
C Correct answer
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).