Physics

Wave Motion

489 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 properties of waves longitudinal and transverse waves travelling waves types of waves

For propagation of a mechanical wave, the medium must possess

  1. inertia

  2. conductivity

  3. plasticity

  4. elasticity
Reveal answer Fill a bubble to check yourself
A,D Correct answer
Explanation
  • MEDIUM SHOULD BE ISOTROPIC: The properties of the medium should be the same in all directions.
  • ELASTICITY : The medium should have elasticity so that the particles return back to their original positions after being displaced.
  • INERTIA : This allows the particles to store kinetic energy.
  • MINIMUM FRICTION : So that the particles oscillate and the wave travels for a sufficiently long time and distance.
  • these were the properties required for propagation of mechanical waves , so the answer is A and D.
Multiple choice physics properties of waves longitudinal and transverse waves travelling waves types of waves

Water waves are an example of waves that involve

  1. longitudinal motions.

  2. transverse motions.

  3. a combination of both longitudinal and transverse motions

  4. some unknown type of motions,
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Water waves are an example of waves that involve a combination of both longitudinal and transverse motions. As a wave travels through the waver, the particles travel in clockwise circles. The radius of the circles decreases as the depth into the water increases.

so the answer is C.

Multiple choice physics properties of waves longitudinal and transverse waves travelling waves types of waves

Which of the following statements are true for wave motion ?

  1. Mechanical transverse waves can propagate through all mediums

  2. Longitudinal waves can propagate through solids only

  3. Mechanical transverse waves can propagate through solids only

  4. Longitudinal waves can propagate through vacuum
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

$1.$ Mechanical transverse waves cannot propagate through all the medium. They can only propagate through solids not in gas or a liquid because there is no mechanism for driving motion perpendicular to the propagation of the wave.

$2.$ Longitudinal wave can propagate through all type of medium.
$3.$ Mechanical transverse wave can propagate through solids only.
$4.$ Longitudinal wave cannot propagate through vaccum.
Hence, option $C$ is correct.

Multiple choice physics sound and noise musical sound and scale pleasant, unpleasant sounds and noise pollution sound noise and pollution

Amplitude of wave is:

  1. the distance wave moves in one second

  2. distance wave moves in one time period of wave

  3. maximum distance moved by medium particles on either side of mean position

  4. distance equal to 1 wavelength
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Amplitude is the maximum distance moved by medium particles on either side of mean position.

Multiple choice physics superposition of waves coherence young's double slit experiment interference

If two sources have a randomly varying phase difference $\varphi ( t )$  the resultant intensity will be given by 

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

Phase difference is $\phi (t)$,

Since, the phase difference is varying, then the waves are said to be incoherent. So, the intensity of resultant wave is the sum of intensities of each wave i.e. $2\,{{I} _{0}}$ 

Multiple choice physics superposition of waves coherence young's double slit experiment interference

Two sources are called coherent if they produce waves

  1. of equal wavelength

  2. of equal velocity

  3. having same shape of wavefront

  4. having a constant phase different
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Two source are called coherent, if they have constant phase difference i.e., phase difference between two wave is constant with respect to time.

Multiple choice physics superposition of waves coherence young's double slit experiment interference

Two waves having the same wavelength and amplitude but having a constant phase difference with time are known as :

  1. identical waves

  2. incoherent waves

  3. coherent waves

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

When the light waves are emitted from a single source and they have a constant phase difference between them then the waves are said to be coherent.
Option C is correct .

Multiple choice physics superposition of waves coherence young's double slit experiment interference

The equations of waves emitted $S _1,S _2,S _3$ and $S _4$ are respectively $y _1=20\sin(100\pi t), y _2=20\sin(200\pi t), y _3=20\cos(100\pi t)$ and $y _4=20\cos(100\pi t)$. The phenomenon of interference will be produced by 

  1. $y _1$ and $y _2$
  2. $y _2$ and $y _3$
  3. $y _1$ and $y _3$

  4. Interference will not possible
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
To set up a stable and clear interference pattern, two conditions must be met:
The sources of the waves must be coherent, which means they emit identical waves with a constant phase difference.
And the waves should be monochromatic - they should be of a single wavelength.
Since the frequency of $y _1$ and $y _2$ is same, they form interference pattern.
Multiple choice physics superposition of waves coherence young's double slit experiment interference

For interference to take place

  1. sources must be coherent

  2. sources must have same amplitude

  3. waves should travel in opposite directions

  4. sources must have same frequency
Reveal answer Fill a bubble to check yourself
A,D Correct answer
Explanation

For interference to take place source must be coherent, which implies:

  • Same frequency for the two waves
  • Constant phase difference.
Options A and D match.

Multiple choice physics refraction of light optical fibre the critical angle, total internal reflection and optical fibre total internal reflection

A plane sound wave travelling with velocity $v$ in a medium $A$ reaches a point on the interface of medium $A$ and medium $B$. If velocity of sound in medium $B$ is $2v$, the angle of incidence for total internal reflection of the wave will be greater than ($\sin{30} = 0.5$ and $\sin{90} = 1$)

  1. $15$
  2. $30$
  3. $45$
  4. $90$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Light travel from medium $A$ with velocity $v$ to medium $B$ with velocity $2v$
Velocity is more in medium $B$, hence it is rarer.
Refractive index of medium $A$ with respect to medium $B$
$\mu = _{B}{\mu} _{A} = \dfrac{Velocity  \ in \  medium \  B}{Velocity \  in   \ medium  \ A}$
$ _{B}{\mu} _{A} = {2}/{1}$
Now as       $\sin{C} = \dfrac{1}{\mu} $

$   \therefore   \sin{C} = \dfrac{1}{2} = 0.5$
$\Rightarrow        C = 30$