A progressive wave ${\rm{y = a}}\,{\rm{sin}}\left[ {\left( {{\rm{kx}} - {\rm{\omega t}}} \right)} \right]$ is reflected by a rigid wall at ${\rm{x}} = 0$. Then the reflected wave can be represented by

$\begin{array}{*{20}{l}} {{\rm{y = }} - {\rm{asin}}\left( {{\rm{kx + \omega t}}} \right)} \end{array}$

${\rm{y = a}}\,{\rm{sin}}\left( {{\rm{kx + \omega t}}} \right)$

$\begin{array}{*{20}{l}} {{\rm{y = a}}\,{\rm{cos}}\left( {{\rm{kx + \omega t}}} \right)} \end{array}$

$\begin{array}{*{20}{l}} {{\rm{y}} = - {\rm{asin}}\left( {{\rm{kx}} - {\rm{\omega t}}} \right)} \end{array}$

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JEE • PHYSICS • WAVES

Waves practice · Medium

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These sets use single-correct-answer MCQs. They do not cover every JEE Main or JEE Advanced question format and are not full-length mock papers.

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Showing 1-30 of 524 questions

1 Medium

1 of 524

Application +4 | -1

The source of sound generating a frequency of

3\,\,kHz

reaches an observer with a speed of

0.5

times, the velocity of sound in air. The frequency heard by the observer is

View answer and explanation

Correct option: D

6\mathrm{ }kHz

Option D (

6\mathrm{ }kHz

) is correct because it is the frequency observed when the source is moving towards the observer at half the speed of sound, calculated using the Doppler effect formula.

2 Medium

2 of 524

Application +4 | -1

A source of sound emits waves with frequency

f\mathrm{ }Hz

and speed

V\mathrm{ }m/sec

. Two observers move away from this source in opposite directions each with a speed

0.2\,\,V

relative to the source. The ratio of frequencies heard by the two observers will be

View answer and explanation

Correct option: C

1:1

Option C (1:1) is correct because both observers are moving away from the source at the same speed, so the Doppler shift will be the same in magnitude, resulting in the same observed frequency ratio.

3 Medium

3 of 524

Analyzing +4 | -1

Assertion: The wave function of a pulse is given by

y = \frac{3}{{{{\left( {2x + 3t} \right)}^2} + 4}},

it propagates in

(– \mathrm{ve}) \,x

-direction.
Reason: The given wave function is of the form

y = f(kx +\omega t),

which represent a wave travelling in negative

X

-direction.

View answer and explanation

Correct option: A

If both Assertion & reason are True & the Reason is a correct explanation of the Assertion

Option A is correct because the wave function's form and the sign convention of the argument (kx + ωt) indicate propagation in the negative x-direction.

4 Medium

4 of 524

Application +4 | -1

In the fundamental mode, time taken by the wave to reach the closed end of the air filled pipe is

0.01\,\,s

. the fundamental frequency is

View answer and explanation

Correct option: A

Option A (25) is correct because the fundamental frequency is calculated using the time taken for the wave to reach the closed end of the pipe.

5 Medium

5 of 524

Application +4 | -1

A rope

5 \mathrm{~m}

long has a total mass of

245 \mathrm{~g}

. It is stretched with a constant tension of

1 \mathrm{~kg}

wt. If it is fixed at one end and shaken by hand at the other end, what frequency of shaking will make it break up into three vibrating segments? Take

g=980 \mathrm{~cm} \mathrm{~s}^{-2}

View answer and explanation

Correct option: D

4.24 \mathrm{~Hz}

Option D (

4.24 \mathrm{~Hz}

) is correct because it is calculated using the formula for the frequency of vibration in a string fixed at one end, considering the number of segments.

6 Medium

6 of 524

Remembering +4 | -1

T

is the reverberation time of an auditorium of volume

V

then

View answer and explanation

Correct option: D

T \propto V

Option D (

T \propto V

) is correct because the reverberation time is directly proportional to the volume of the auditorium.

7 Medium

7 of 524

Understanding +4 | -1

In stationary waves, antinodes are the points where there is

View answer and explanation

Correct option: D

Maximum displacement and minimum pressure change

Option D (Maximum displacement and minimum pressure change) is correct because antinodes in stationary waves have maximum displacement and minimum pressure change.

8 Medium

8 of 524

Understanding +4 | -1

Assertion: The reverberation time dependent on the volume of enclosure.
Reason: The unit of absorption coefficient is sabine.

View answer and explanation

Correct option: B

If both assertion and reason are true but reason is not the correct explanation of assertion

Option B is correct because both the assertion and the reason are true, but the reason does not explain the assertion. Reverberation time depends on volume, and the unit of absorption coefficient is sabine, but these are independent facts.

9 Medium

9 of 524

Application +4 | -1

When the length of the vibrating segment of a sonometer wire is increased by

1\%

the percentage changes its frequency is

View answer and explanation

Correct option: C

Option C (1) is correct because a 1% increase in length results in approximately a 1% decrease in frequency, given the inverse relationship.

10 Medium

10 of 524

Understanding +4 | -1

Resonance occurs, when:

View answer and explanation

Correct option: C

A body is set into vibrations with its natural frequency, by another body vibrating with the same frequency

Option C (A body is set into vibrations with its natural frequency, by another body vibrating with the same frequency) is correct because resonance occurs when the driving frequency matches the natural frequency.

11 Medium

11 of 524

Application +4 | -1

Calculate the ratio of the speed of sound in neon to that in water vapour at any temperature. [Molecular weight of neon

=2.02 \times 10^{-2} \mathrm{~kg} / \mathrm{mol}

and for water vapours

=1.8 \times

\left.10^{-2} \mathrm{~kg} / \mathrm{mol}\right]

View answer and explanation

Correct option: A

1.05

Option A (1.05) is correct because it is the ratio of the speed of sound in neon to that in water vapor, calculated using the formula

v = \sqrt{\frac{\gamma RT}{M}}

12 Medium

12 of 524

Analyzing +4 | -1

Assertion: A balloon filled with

CO_2

gas acts as a converging lens for a sound wave.
Reason: Sound waves travel faster in air than in

CO_2.

View answer and explanation

Correct option: A

If both Assertion & reason are True & the Reason is a correct explanation of the Assertion

Option A is correct. A CO2 balloon acts as a converging lens because sound travels slower in CO2 than in air, and sound waves travel faster in air than in CO2 is the correct reason.

13 Medium

13 of 524

Understanding +4 | -1

What is the phase difference between two successive crests in the wave?

View answer and explanation

Correct option: C

\pi

Option C (2

\pi

) is correct because the phase difference between two successive crests (or troughs) in a wave is one full wavelength, which corresponds to 2

\pi

radians.

14 Medium

14 of 524

Analyzing +4 | -1

A tunning fork of frequency of

512 \mathrm{~Hz}

when sounded with unknown tunning fork produces 5 beats/sec. If arms of the unknown fork are filed then it produces only 3 beats / sec. Find the frequency of unknown tunning fork.

View answer and explanation

Correct option: A

517 Hz

Option A (517 Hz) is correct because filing the arms of the unknown fork increases its frequency, and the beat frequency decreases, indicating that the unknown frequency was initially higher than 512 Hz.

15 Medium

15 of 524

Understanding +4 | -1

Doppler’s effect in sound is due to

View answer and explanation

Correct option: C

Relative motion of source and observer

Option C (Relative motion of source and observer) is correct because Doppler's effect depends on the relative velocity between the source of the sound and the observer.

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16 Medium

16 of 524

Understanding +4 | -1

A source emits sound of frequency

600 \mathrm{~Hz}

inside water. The frequency heard in air will be equal to (velocity of sound in water

=1500 \mathrm{~m} / \mathrm{s}

, velocity of sound in air

=300

\mathrm{m} / \mathrm{s})

View answer and explanation

Correct option: C

600 \mathrm{~Hz}

Option C (

600 \mathrm{~Hz}

) is correct because the frequency of sound remains the same when it travels from one medium to another.

17 Medium

17 of 524

Application +4 | -1

A glass tube of length

1.0 {~m}

is completely filled with water. A vibrating tuning fork of frequency

500 {~Hz}

is kept over the mouth of the tube and the water is drained out slowly at the bottom of the tube. If the velocity of sound in air is

330 {~ms}^{-1}

, then the total number of resonances that occur will be

View answer and explanation

Correct option: B

Option A (3) is correct because there are three resonance lengths within the 1-meter tube length for the given frequency.

18 Medium

18 of 524

Application +4 | -1

A person can hear sound waves in the frequency range

20 \mathrm{~Hz}

20\,\mathrm{kHz}

. Find the minimum and the maximum wavelengths of sound that is audible to the person. The speed of sound is

360 \mathrm{~ms}^{-1}

View answer and explanation

Correct option: A

18 mm, 18 m

Option A (18 mm, 18 m) is correct because it correctly calculates the minimum and maximum wavelengths using the given frequency range and speed of sound.

19 Medium

19 of 524

Understanding +4 | -1

An empty vessel is partially filled with water, then the frequency of vibration of air column in the vessel

View answer and explanation

Correct option: C

Increases

Option C (Increases) is correct because as the water level rises, the length of the air column decreases, leading to a higher frequency of vibration.

20 Medium

20 of 524

Remembering +4 | -1

Law of superposition is applicable to

View answer and explanation

Correct option: D

All kinds of waves

Option D (All kinds of waves) is correct because the principle of superposition applies to all types of waves, including light, sound, and transverse waves, as long as the waves are in a linear medium.

21 Medium

21 of 524

Understanding +4 | -1

Statement-I: When a sound wave is propagating through the medium the acceleration of a particle is directly proportional to its displacement.
Statement-II: Wave velocity depends on the properties of the medium and is independent of time and position.

View answer and explanation

Correct option: C

Both statement-I

\&

II are correct

Option C is correct because both statements are true: acceleration is proportional to displacement in a sound wave, and wave velocity depends on medium properties.

22 Medium

22 of 524

Understanding +4 | -1

Assertion: Solids can support both longitudinal and transverse waves but only longitudinal waves can propagate in gases.
Reason: For the propagation of transverse waves, medium must also necessarily have the property of rigidity.

View answer and explanation

Correct option: A

If both assertion and reason are true and reason is the correct explanation of the assertion

Option A is correct because transverse waves require rigidity, which solids possess but gases do not, while longitudinal waves can propagate in both.

23 Medium

23 of 524

Application +4 | -1

The ratio of intensities between two coherent sound sources is

4:1

. The difference of loudness in decibels

\left( {\mathrm{dB}} \right)

between maximum and minimum intensities, on their interference in space is

View answer and explanation

Correct option: C

20\,\,\log 3

Option C (

20\,\,\log 3

) is correct because the difference in loudness is calculated using the ratio of maximum to minimum intensities, which depends on the amplitude ratio of the sound sources.

24 Medium

24 of 524

Understanding +4 | -1

A progressive wave 

\mathrm{y = a}\,\mathrm{sin}\left[ {\left( {\mathrm{kx} - \mathrm{\omega t}} \right)} \right]

is reflected by a rigid wall at

\mathrm{x} = 0

. Then the reflected wave can be represented by

View answer and explanation

Correct option: D

\begin{array}{llllllllllllllllllll} {\mathrm{y = } - \mathrm{asin}\left( {\mathrm{kx + \omega t}} \right)} \end{array}

Option D is correct because reflection from a rigid wall introduces a phase change of π, resulting in a negative sign and a change in direction.

25 Medium

25 of 524

Understanding +4 | -1

In a stationary wave system, all the particles of the medium;

View answer and explanation

Correct option: D

All of the above

Option D (All of the above) is correct because in a stationary wave, all particles reach zero displacement, maximum displacement, and are at rest simultaneously at some instant.

26 Medium

26 of 524

Understanding +4 | -1

Assertion: A tuning fork is made of an alloy of steel, nickel and chromium.
Reason: The alloy of steel, nickel and chromium is called elinvar.

View answer and explanation

Correct option: B

If both assertion and reason are true but reason is not correct explanation of the assertion

Option B is correct because both the assertion and reason are true, but the reason does not explain why that particular alloy is used for tuning forks.

27 Medium

27 of 524

Analyzing +4 | -1

The wavelength of two notes in air are

\frac{{36}}{{195}}m

and

\frac{{36}}{{193}}m

each note produces

10

beats per second separately with a third note of fixed frequency. The velocity of sound in air in

m/s

View answer and explanation

Correct option: D

360

Option D (

360

) is correct because it is calculated using the beat frequency formula and the given wavelengths.

28 Medium

28 of 524

Application +4 | -1

Two points on a travelling wave having frequency

500\,\,Hz

and velocity

300\,\,\mathrm{m}{\mathrm{s}^{ - 1}}

are

60^\circ

out of phase, then the minimum distance between two points is

View answer and explanation

Correct option: B

0.1

Option B (0.1) is correct because the minimum distance between two points with a 60-degree phase difference is calculated using the wavelength and the phase difference.

29 Medium

29 of 524

Understanding +4 | -1

A wave is reflected from a rigid support. The change in phase on reflection will be

View answer and explanation

Correct option: C

\pi

Option C is correct because a wave reflected from a rigid support undergoes a phase change of \

\pi

radians.

30 Medium

30 of 524

Understanding +4 | -1

If the temperature of the atmosphere is increased, the following character of the sound wave is effected

View answer and explanation

Correct option: C

Velocity

Option C (Velocity) is correct because the speed of sound in a gas is directly proportional to the square root of the temperature, so an increase in temperature increases the velocity of sound.

Revision notes and key takeaways

Review WAVES in your textbook or class notes, then use this set to check your understanding.

Key Takeaways

✓ This set contains 524 single-correct-answer MCQs on WAVES.
✓ Try each question before opening its answer. Read the explanation where one is available.
✓ Sign in to save submitted answers. Revisit incorrect answers alongside your textbook or class notes.

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