# MCQ Questions for Class 11 Physics Chapter 15 Waves with Answers

We have compiled the NCERT MCQ Questions for Class 11 Physics Chapter 15 Waves with Answers Pdf free download covering the entire syllabus. Practice MCQ Questions for Class 11 Physics with Answers on a daily basis and score well in exams. Refer to the Waves Class 11 MCQs Questions with Answers here along with a detailed explanation.

## Waves Class 11 MCQs Questions with Answers

Multiple Choice Type Questions

Question 1.
The speed of sound in a medium depends upon
(a) its elasticity as well as its inertia.
(b) its elasticity but not its inertia.
(c) its inertia but not its elasticity.
(d) neither its elasticity nor its inertia.

Answer: (a) its elasticity as well as its inertia.

Question 2.
The velocity of sound in a gas is proportional to :
(a) the isothermal elasticity.
(c) square root of the isothermal elasticity.
(d) square root of the adiabatic elasticity.

Question 3.
Whenever a wave enters from one medium to the another, its
(a) velocity changes.
(b) frequency changes.
(c) frequency does not change.
(d) wavelength remains constant.

Answer: (c) frequency does not change.

Question 4.
The velocity of sound in any gas depends upon
(a) wavelength of sound only.
(b) amplitude and frequency of sound.
(c) density and elasticity of the gas.
(d) intensity of sound waves only.

Answer: (c) density and elasticity of the gas.

Question 5.
The elastic or matter waves in a solid are
(а) longitudinal.
(b) transverse.
(c) either longitudinal or transverse.
(d) neither longitudinal nor transverse.

Answer: (c) either longitudinal or transverse.

Question 6.
With the propagation of longitudinal wave through a material medium, the quantities transmitted in the propagation direction are :
(a) energy.
(b) energy and linear momentum.
(c) energy and mass.
(d) energy, mass and momentum.

Question 7.
When a tuning fork vibrates, the waves produced in tuning the Fork are
(a) transverse both in the prongs and the stem.
(b) longitudinal in both the prongs and stem.
(c) longitudinal in stem and transverse in prongs.
(d) longitudinal in prongs and transverse in the stem.

Answer: (c) longitudinal in stem and transverse in prongs.

Question 8.
Name the characteristics of the sound that are affected by the change in temperature.
(a) amplitude
(b) frequency
(c) intensity
(d) wavelength

Question 9.
The standing waves can be produced
(a) on a string clamped at both the ends.
(b) on a string clamped at one end and free at the other end.
(c) when the incident wave gets reflected from a wall.
(d) when two identical waves with a phase difference of K are moving in the same direction.

Question 10.
Name the type of vibrations that are produced in a sitar wire
(a) progressive transverse.
(b) progressive longitudinal.
(c) stationary longitudinal.
(d) stationary transverse.

Question 11.
An organ pipe, open at both the ends, produces
(a) longitudinal progressives waves.
(b) longitudinal stationary waves.
(c) transverse stationary waves.
(d) transverse progressive waves.

Question 12.
Beats are the result of:
(a) diffraction.
(b) constructive interference.
(c) destructive interference.
(d) superposition of two waves of nearly equal frequencies.

Answer: (d) superposition of two waves of nearly equal frequencies.

Question 13.
The factor that helps to recognise a person by his voice is
(a) intensity
(b) pitch
(c) loudness
(d) quality

Question 14.
Pitch depends upon the
(a) amplitude
(b) wavelength
(c) frequency
(d) speed

Question 15.
Decibel is the anil of:
(a) sound intensity
(b) heat intensity
(c) light intensity
(d) all of the above

Question 16.
The quality of a note changes when change occurs in the
(a) pitch
(b) loudness
(c) wavelength
(d) nature of overtones.

Question 17.
Reverberation is caused by
(a) refraction
(b) absorption
(c) reflection
(d) interference

Question 18.
A sound is said to be of rich quality, when it
(a) contains overtones
(b) does not contain overtones
(c) is a note of high frequency
(d) is a note of high amplitude

Question 19.
The sound of minimum frequency emitted by a vibrating string is not termed as
(a) first harmonic
(b) first overtone
(c) fundamental tone
(d) none of the above

Question 20.
What types of waves are produced in the sonometer wire?
(a) Transverse and stationary.
(b) Transverse and progressive.
(c) Longitudinal and progressive.
(d) Longitudinal and stationary.

Question 21.
A source of sound moves towards a stationary listener. The apparent pitch of the sound is found to be higher than its actual value. This happens because
(a) wavelength of the sound increases.
(b) wavelength of the sound decreases.
(c) the number of waves received by the listener decreases.
(d) the number of waves received by the listener increases.

Answer: (b) wavelength of the sound decreases.

Question 22.
In an open organ pipe, which harmonics are missing?
(a) even.
(b) odd.
(c) depends upon the length of the pipe.
(d) none of the above.

Answer: (d) none of the above.

Fill in the blanks

Question 1.
The superposition principle is not obeyed by ………………. waves.

Question 2.
The mechanical waves ………………. a material medium for propagation but e.m. waves ……………….

Question 3.
In a sound wave, a displacement node is a ………………. an inode and vice-versa.

Question 4.
The reverberation time is ………………. for a crowded hall than for an empty hall.

Question 5.
The particle of the medium permanently at rest are called ………………. whereas those having maximum displacements are called ……………….

Question 6.
The minimum wavelength of sound audible to the human ear is nearly ……………….

Question 7.
The Doppler effect is a phenomenon and can be experienced both in ………………. waves and ………………. waves.

Question 8.
The sound produced in the string of a sonometer plucked so as to make it vibrate in one segment is called ……………….

Question 9.
The vibrations produced into a microphone when we speak are ……………….

Question 10.
A pure sine wave of sound is called ……………….

Question 11.
………………. does not has a subjective existance.

Question 12.
The elastic waves in solid are ……………….

Question 13.
The minimum frequency with which the standing waves can be set up in the string fixed at its both ends is called ……………….

Answer: first harmonic or pitch of the tone

Question 14.
………………. harmonics are absent in a pipe open at one end and closed at the other.

Question 15.
A periodic wave function of sine or cosine form is called ……………….

Question 16.
………………. waves are produced when two progressive waves of same frequency moving with same speed in opposite direction in a medium superpose on each other.

Question 17.
In case of a vibrating rod, the restoring force is provided by ………………. but in case of a vibrating string, the restoring force is provided by ……………….

Question 18.
Sound speed increases by 0.61 ms-1 for every ………………. in temperature.

Question 19.
Nodes and antinodes are separated by ……………….

Answer: $$\frac {π}{4}$$

Question 20.
Two successive nodes or antinodes are separated by ……………….

Answer: $$\frac {π}{2}$$

Question 21.
Doppler’s effect is a consequence of ………………. between the source of sound and the listener.

Question 22.
The speed of sound in air is not affected by the change in ……………….

Question 23.
……………… waves are also called as mechanical waves.

True/False Type Questions

1. Mark True/False statements
(a) The pitch of the sound as detected by the observer depends on the original frequency.
(b) For two systems to be in resonance, their frequencies must be equal.
(c) Elasticity and inertia are responsible for propagation of sound waves through a medium.

(a) True
(b) True
(c) True

2. Mark True/False statements :
(a) Transverse waves are produced on water surface.
(b) Speed of transverse waves through a solid depends on its density and modulus of rigidity.
(c) The multiple reflection of sound of lightning causes the rolling sound of thunder.

(a) True
(b) True
(c) True

3. Mark True/False statements
(a) The range of audible sound is 20 Hz to 20 kHz.
(b) The infrasonics are the sounds of frequencies less than 20 Hz.
(c) The ultrasonics are the sounds of frequencies more than 20 kHz Le. 20,000 Hz.

(a) True
(b) True
(c) True

4. Mark the True/False statements
(a) The angle between the particle velocity and the wave velocity is 0° or 180° in case of longitudinal waves.
(b) The angle between the particle velocity and the wave velocity in case of transverse waves is $$\frac {π}{2}$$.
(c) The distance between the two nearest particles in the same phase is called wavelength.

(a) True
(b) True
(c) True

5. Mark True/False statements
(a) Transverse waves travel in the form of crests and troughs.
(b) Longitudinal waves travel in the form of compressions and rarefactions.
(c) Sound waves can travel in vacuum.

(a) True
(b) True
(c) False

6. Mark True/False statements
(a) The phase difference between two nearest crests is 2π or zero.
(b) The phase difference between a crest and its nearest trough is π.
(c) A phase difference of π is introduced in the wave on reflection from a denser medium.
(d) No phase difference is introduced in the wave on reflection from a rarer medium.

(a) True
(b) True
(c) True
(d) True

7. Mark True/False statements
(a) The velocity of sound waves in air at 0°C is 332 ms-1.
(b) The velocity of sound is more in dry air than in moist air.
(c) The velocity of sound is more in hydrogen than in oxygen.

(a) True
(b) False
(c) True

8. Mark True/False statements
(b) The frequency of a tuning fork increases on filing.
(c) The ultrasonic waves in air produced by a vibrating quartz crystal are longitudinal.

(a) True
(b) True
(c) True

9. Mark True/False statements
(a) The wavelength increases when the source of sound moves away from the stationary observer.
(b) When the observer moves towards the stationary source of sound, the frequency increases.

(a) True
(b) True

10. Mark True/False statements
(a) We can locate the position of nodes and antinodes in a string by using a light paper rider.
(b) The rider does not move at the nodes and it jumps vigorously at the antinodes.
(c) The sound of higher quality is sweater.
(d) The presence of audience in a hall reduces the reverberation time.

(a) True
(b) True
(c) True
(d) True

Match Type Questions

 Column I Column II (a) Intensity of sound. (i) the apparent frequency of sound appears to decrease. (b) When the source of sound moves away from the stationary listener. (ii) the apparent frequency of the sound appears to decrease. (c) When the listener moves away from the source of sound at rest. (iii) $$\frac {energy transferred}{time × area}$$ (d) Doppler’s effect (iv) phenomenon of change in the apparent pitch due to relative motion between the source of sound and the listener.

 Column I Column II (a) Intensity of sound. (iii) $$\frac {energy transferred}{time × area}$$ (b) When the source of sound moves away from the stationary listener. (i) the apparent frequency of sound appears to decrease. (c) When the listener moves away from the source of sound at rest. (ii) the apparent frequency of the sound appears to decrease. (d) Doppler’s effect (iv) phenomenon of change in the apparent pitch due to relative motion between the source of sound and the listener.

 Column I Column II (a) When both the source and the listener move towards each other. (i) remains same in both cases. (b) When the both source and the listener move away from each other. (ii) the apparent frequency will be more than the actual frequency. (c) Relative velocity of sound w.r.t. the source approaching or receding the listener at rest. (iii) the apparent frequency may be greater or less than the actual frequency depending upon vθ <> vs.

 Column I Column II (a) When both the source and the listener move towards each other. (ii) the apparent frequency will be more than the actual frequency. (b) When the both source and the listener move away from each other. (iii) the apparent frequency may be greater or less than the actual frequency depending upon vθ <> vs. (c) Relative velocity of sound w.r.t. the source approaching or receding the listener at rest. (i) remains same in both cases.

 Column I Column II (a) is equal to the difference between the frequencies of two component waves (i) rω (b) wave velocity (ii) vλ (c) particle velocity or velocity amplitude (iii) beat frequency

 Column I Column II (a) is equal to the difference between the frequencies of two component waves (iii) beat frequency (b) wave velocity (ii) vλ (c) particle velocity or velocity amplitude (i) rω

 Column I Column II (a) elastic waves (i) v = $$\sqrt{\frac {η}{ρ}}$$ (b) electromagnetic or non-mechanical waves (ii) sound waves (c) speed of transverse waves in a solid (iii) light waves

 Column I Column II (a) elastic waves (ii) sound waves (b) electromagnetic or non-mechanical waves (iii) light waves (c) speed of transverse waves in a solid (i) v = $$\sqrt{\frac {η}{ρ}}$$

 Column I Column II (a) Transverse wave motion (i) longitudinal wave (b) Longitudinal wave motion (ii) travels in the form of crests and troughs (c) Sound waves (iii) travels in the form of compressions and rarefactions (d) X- rays (iv) transverse wave

 Column I Column II (a) Transverse wave motion (ii) travels in the form of crests and troughs (b) Longitudinal wave motion (iii) travels in the form of compressions and rarefactions (c) Sound waves (i) longitudinal wave (d) X- rays (iv) transverse wave

 Column I Column II (a) Speed of longitudinal waves in a liquid or gas. (i) v = $$\sqrt{\frac {K}{ρ}}$$ (b) Speed of longitudinal waves in a solid in the long rod form. (ii) v = $$\sqrt{\frac {K_{adi}}{ρ}}$$ = $$\sqrt{\frac {γP}{ρ}}$$ (c) Newton’s formula for speed of sound in a gas. (iii) v = $$\sqrt{\frac {K_iso}{ρ}}$$ = $$\sqrt{\frac {P}{ρ}}$$ (d) Laplace’s correct formula for speed of sound in a gas (iv) v = $$\sqrt{\frac {Y}{ρ}}$$

 Column I Column II (a) Speed of longitudinal waves in a liquid or gas. (i) v = $$\sqrt{\frac {K}{ρ}}$$ (b) Speed of longitudinal waves in a solid in the long rod form. (iv) v = $$\sqrt{\frac {Y}{ρ}}$$ (c) Newton’s formula for speed of sound in a gas. (iii) v = $$\sqrt{\frac {K_iso}{ρ}}$$ = $$\sqrt{\frac {P}{ρ}}$$ (d) Laplace’s correct formula for speed of sound in a gas (ii) v = $$\sqrt{\frac {K_{adi}}{ρ}}$$ = $$\sqrt{\frac {γP}{ρ}}$$

 Column I Column II (a) Travelling or progressive wave (i) two travelling waves of same wavelength and amplitude travelling with same speed in opposite direction in a medium and superpose each other. (b) Standing wave (ii) a wave travelling continuously in a medium in the same direction without any change in its amplitude. (c) Beats (iii) when two waves of slightly different frequency moving with the same speed in the same direction in a medium superpose each other.

 Column I Column II (a) Travelling or progressive wave (ii) a wave travelling continuously in a medium in the same direction without any change in its amplitude. (b) Standing wave (i) two travelling waves of same wavelength and amplitude travelling with same speed in opposite direction in a medium and superpose each other. (c) Beats (iii) when two waves of slightly different frequency moving with the same speed in the same direction in a medium superpose each other.

 Column I Column II (a) Pressure variation is minimum. (i) Bel (b) Pressure variation is maximum. (ii) Nodes (c) Unit of loudness. (iii) Antinodes (d) Unit of intensity. (iv) watt/m²

 Column I Column II (a) Pressure variation is minimum. (iii) Antinodes (b) Pressure variation is maximum. (ii) Nodes (c) Unit of loudness. (i) Bel (d) Unit of intensity. (iv) watt/m²

 Column I Column II (a) Prolongation of sound after the source has. ceased to produce sound. (i) Reverberation (b) The duration for which the sound can be heard after the source has. ceased to produce sound. (ii) Reverberation (c) A room with zero reverberation time. (iii) Dead room