Physics

Wave Motion

536 Questions

Wave motion questions cover the principles of traveling and stationary waves, including their equations and intensities. The topics explore interference patterns, phase differences, and electromagnetic radiation speeds. Mastery of these concepts is vital for physics sections in engineering and civil services examinations.

Wave interferenceStanding wavesPhase differenceElectromagnetic radiationWave equations

Wave Motion Questions

Multiple choice physics wave optics huygens wave theory and wavefront wave propagation (huygens' construction) theories on light wave behaviour

A transverse wave travelling in a denser medium is reflected from a rarer medium. Then, 

  1. an incident crest is reflected as a crest

  2. an incident crest is reflected as a trough
  3. there is a phase change of $2\pi$ rad
  4. there is a phase change of $\pi/2$ rad
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

When a wave reflects from a rarer medium, there is no phase change. Therefore, the crest remains a crest and the trough remains a trough.

Multiple choice physics wave optics huygens wave theory and wavefront wave propagation (huygens' construction) theories on light wave behaviour

The wave front due to a source situated at infinity is :

  1. spherical

  2. cylindrical

  3. planar

  4. none of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
  • when you considered it a large distance and measuring justice Mall section of it then it can be considered to be plane wavefront source at Infinity 
  • example the one coming from sun to earth surface is considered to be plain VU friend from light diverging from a point source will be spherical
  • So, the wave front due to a source situated at infinity is planar
  • Option  C is the right answer
Multiple choice physics wave optics huygens wave theory and wavefront wave propagation (huygens' construction) theories on light wave behaviour

A : The phase difference between any two points on a wave front is zero
R : From the source light, reaches every point on the wave front in the same time.

  1. Both A and R are true, and R is correct explanation of A

  2. Both A and R are true, and R is not correct explanation of A

  3. A is true but R is false

  4. A is false but R is true
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A wave front is the locus of points having the same phase.
Thus statement A is true because the phase difference is zero as all points have same phase.
Statement R is true because a wavefront is composed of all points where the light reaches from the source in the same time.
As light takes the same time it has the same phase at all points on a wavefront and hence it correctly explains statement A.

Multiple choice physics wave optics huygens wave theory and wavefront wave propagation (huygens' construction) theories on light wave behaviour

1: Primary waves can travel in all directions in an ether
2: Secondary waves can travel only in backward in an ether

  1. 1 is true, 2 is false

  2. Both 1 and 2 are true

  3. 1 is false, 2 is true

  4. Both 1 and 2 are false
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Primary wave can travel in all directions in ether.
Secondary waves can travel in forward direction in ether

Multiple choice physics wave optics huygens wave theory and wavefront wave propagation (huygens' construction) theories on light wave behaviour

A wave pulse traveling on a two piece string, gets partially reflected and partially transmitted at the junction. The reflected wave is inverted in shape as compared to incident one. If the incident wave has wavelength  $\lambda$  and transmitted wave has  $\lambda ',$  then

  1. $\lambda '> \lambda$
  2. $\lambda' = \lambda$
  3. $\lambda' < \lambda$

  4. none
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Reflected wave is inverted hence second medium is dir sec with respect to first medium. $\lambda ' < \lambda $

$\frac{{\lambda '}}{t} < \frac{\lambda }{t} \Rightarrow \lambda ' < \lambda $
Ans. (C)

Multiple choice physics study of sound reverberation applications of reflection of sound multiple reflection of sound and reverberation applications of ultrasound

(1) The reflected pulse will be in same orientation of incident pulse due to a phase change of $\pi$ radians.
(2) During reflection the wall exerts a force on string in upward direction.
For the above given two statements choose the correct option given below.

  1. Only (1) is true

  2. Only (2) is true

  3. Both are true

  4. Both are wrong
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The pulse will be of same orientation as before after the phase change of $2\pi$ radians

During the reflection string tries to move upward but wall applies downward force to stop movement of connected end. So both the statements are wrong.

Multiple choice luminous intensity measurements physics

Two coherent source must have the same :

  1. amplitude

  2. phase difference

  3. frequency

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

Two coherent source have the same :

1) Frequency
2) Phase difference.

The correct option is D.

Multiple choice physics sound sound as a wave of disturbance vibrations in a tuning fork vibrations in tuning fork

 769Hz longitudinal wave in air has a speed of 344m/s. At a particular instant, what is the phase difference (in degrees) between two points 5.0 cm apart?

  1. 30

  2. 40

  3. 45

  4. 60
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Given that,

The frequency of wave is $\nu = 769 Hz$

The speed of wave is $v = 344 ms^{-1}$

The wavelength of wave is given by

$\lambda = \dfrac{v}{\nu}$

$\lambda = \dfrac{344}{769}$

$\lambda = 0.447 m = 44.7 cm$

Hence, the phase difference between two points 5.0 cm apart is

$\dfrac{5}{44.7} \times 360^\circ = 0.1118 \times 360^\circ = 40.24^\circ \approx40^\circ$

Multiple choice physics sound sound as a wave of disturbance vibrations in a tuning fork vibrations in tuning fork

Sound waves of wavelength $\lambda $ travelling with velocity $v$ in a medium enter into another medium in which their velocity is $4v$. The wavelength in $2^{nd}$ medium is :

  1. $4\lambda$
  2. $\lambda $
  3. $\lambda/4 $
  4. $ 16\lambda $
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

From $v=n\lambda $ we find $\lambda\propto v$ because frequency n is constant .

Therefore ,
new wavelength = $4\lambda $

Multiple choice physics stationary waves sound as a wave of disturbance vibrations in a tuning fork vibrations in tuning fork

The wave produced in a resonance tube is

  1. Longitudinal

  2. Transverse

  3. Transverse stationary

  4. Longitudinal stationary
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Waves produced in a resonance tube are sound waves. Two sound waves in opposite direction interfere with each other to create resonance. As sound waves are longitudinal waves, waves produced are longitudinal stationary. 

Multiple choice physics study of sound sound as a wave of disturbance vibrations in a tuning fork vibrations in tuning fork

A _________________ wave has oscillations in the same direction as its motion.

  1. Longitudinal

  2. Oscillatory

  3. Vibrational

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

A longitudinal wave has oscillations in the same direction as its motion.
Longitudinal waves, also known as l-waves, are waves in which the displacement of the medium is in the same direction as the direction of travel of the wave. Longitudinal waves are also called compressional waves or compression waves, because they produce compression and rarefaction when traveling through a medium.  In longitudinal waves, the displacement of the medium is parallel to the propagation of the wave.