# Class 12 Physics MCQ – Wave Optics – Polarisation

This set of Class 12 Physics Chapter 10 Multiple Choice Questions & Answers (MCQs) focuses on “Wave Optics – Polarisation”.

1. Which type of waves shows the property of polarization?
a) Infrared
b) Longitudinal
c) Transverse
d) Microwave

Explanation: Only transverse waves show the property of polarization. Their vibrations can occur in all directions perpendicular to the direction of travel. The longitudinal, infrared, and microwaves do not show the property of polarization.

2. What will be the angle of refraction in the glass, if the polarization angle for the air-glass interface is 63.8o?
a) 56.3o
b) 33.7o
c) 90o
d) 0o

Explanation: As ip + rp = 90o
rp = 90o – 63.8o
rp = 26.2o
Therefore, the angle of refraction in the glass is 26.2o.

3. What is the polarization angle of a medium of refractive index √3?
a) 60o
b) 120o
c) 30o
d) 90o

Explanation: tan ip = μ = √3.
ip = tan-1(√3)
ip = 60o
Therefore, the polarization angle of a medium of refractive index √3 is 60o.

4. What are sunglasses made of?
a) Colored glasses
b) Tin glass
c) Silica
d) Polaroids

Explanation: Polaroids absorb only that part of the light which produces a dazzling effect in the eye. But colored glasses absorb more light incident on them and so the image appears dim. Therefore, sunglasses are made of Polaroids.

5. Which field vector is used to represent the polarization of an em wave?
a) Potential field vector
b) Magnetic field vector
c) Electric field vector
d) Dipolar field vector

Explanation: An electric field vector is used to represent the polarization of an em wave. It is perpendicular to the plane of propagation of the light wave. Therefore, a vertically polarized electromagnetic wave of wavelength λ has its electric field vector oscillating in the vertical direction.
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6. Sound waves can be polarized.
a) True
b) False

Explanation: Unlike transverse waves such as electromagnetic waves, longitudinal waves such as sound waves cannot be polarized. This is because, sound waves vibrate along their direction of propagation, and thus, cannot be polarized.

7. Identify the property which is not mutually perpendicular to the polarized light wave in a plane.
a) Plane of vibration
b) Plane of rotation
c) Plane of polarization
d) The direction of propagation of the light wave

Explanation: Plane of vibration, the plane of polarization, and direction of propagation of the light wave are mutually perpendicular to the polarized light wave in a plane. The other factors are not mutually perpendicular to the polarized light wave in a plane.

8. Which plane is defined as the plane of polarization in a plane-polarized electromagnetic wave?
a) The plane containing the direction of propagation of light
b) The plane containing the direction of reflective wave
c) The plane containing the direction of refractive wave
d) The plane containing the direction of dispersive wave

Explanation: The plane containing the direction of propagation of light and perpendicular to the plane of vibration is called the plane of polarization. It contains no vibrations. Polarized light waves are light waves in which the vibrations occur in a single plane.

Sanfoundry Global Education & Learning Series – Physics – Class 12.