# Class 11 Physics Chapter 15 Waves MCQ Questions with Answer

Waves Class 11 MCQ is one of the best strategies to prepare for the CBSE Class 11 Board exam. If you want to complete a grasp concept or work on one’s score, there is no method except constant practice. Students can improve their speed and accuracy by doing more MCQ on Waves Class 11, which will help them all through their board test.

## Waves Class 11 MCQ Questions with Answer

Class 11 Physics MCQ with answers are given here to Chapter 15 Waves. These MCQs are based on the latest CBSE board syllabus and relate to the latest Class 11 Physics syllabus. By Solving these Class 11 MCQs, you will be able to analyze all of the concepts quickly in the chapter and get ready for the Class 11 Annual exam.

Learn Class 11 Waves MCQs with answers pdf free download according to the latest CBSE and NCERT syllabus. Students should prepare for the examination by solving CBSE Class 11 Physics Waves MCQ with answers given below

Question 1. A cylindrical tube, open at both ends has fundamental frequency f in air. The tube is dipped vertically in water, so that half of it is in water. The fundamental frequency of air column is now
(a) f /2
(b) 3f /4
(c) 2f
(d) f

D

Question 2. A standing wave having 3 nodes and 2 antinodes is formed between two atoms having a distance 1.21 Å between them. The wavelength of the standing wave is
(a) 6.05 Å
(b) 2.42 Å
(c) 1.21 Å
(d) 3.63 Å

C

Question 3. Standing waves are produced in 10 m long stretched string. If the string vibrates in 5 segments and wave velocity is 20 m/s, the frequency is
(a) 5 Hz A
(b) 10 Hz
(c) 2 Hz
(d) 4 Hz

A

Question 4. A stationary wave is represented by y = Asin (100t) cos (0.01x), where y and A are in millimetres, t is in seconds and x is in metres. The velocity of the wave is
(a) 104 m/s
(b) not derivable
(c) 1 m/s
(d) 102 m/s

A

Question 5. The length of a sonometer wire AB is 110 cm. Where should the two bridges be placed from A to divide the wire in 3 segments whose fundamental frequencies are in the ratio of 1 : 2 : 3 ?
(a) 60 cm and 90 cm
(b) 30 cm and 60 cm
(c) 30 cm and 90 cm
(d) 40 cm and 80 cm

A

Question 6. A wave of frequency 100 Hz travels along a string towards its fixed end. When this wave travels back, after reflection, a node is formed at a distance of 10 cm from the fixed end. The speed of the wave (incident and reflected) is
(a) 20 m/s
(b) 40 m/s
(c) 5 m/s
(d) 10 m/s.

A

Question 7. A stretched string resonates with tuning fork frequency 512 Hz when length of the string is 0.5 m. The length of the string required to vibrate resonantly with a tuning fork of frequency 256 Hz would be
(a) 0.25 m
(b) 0.5 m
(c) 1 m
(d) 2 m

C

Question 8. A closed organ pipe (closed at one end) is excited to support the third overtone. It is found that air in the pipe has
(a) three nodes and three antinodes
(b) three nodes and four antinodes
(c) four nodes and three antinodes
(d) four nodes and four antinodes.

D

Question 9. Three sound waves of equal amplitudes have frequencies (n – 1), n, (n + 1). They superimpose to give beats. The number of beats produced per second will be
(a) 1
(b) 4
(c) 3
(d) 2

D

Question 10. The second overtone of an open organ pipe has the same frequency as the first overtone of a closed pipe L metre long. The length of the open pipe will be
(a) L
(b) 2L
(c) L/2
(d) 4L

B

Question 11. In a guitar, two strings A and B made of same material are slightly out of tune and produce beats of frequency 6 Hz. When tension in B is slightly decreased, the beat frequency increases to 7 Hz. If the frequency of A is 530 Hz, the original frequency of B will be
(a) 523 Hz
(b) 524 Hz
(c) 536 Hz
(d) 537 Hz

B

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Question 12. A source of sound gives 5 beats per second, when sounded with another source of frequency 100 second–1. The second harmonic of the source, together with a source of frequency 205 second–1 gives 5 beats per second. What is the frequency of the source?
(a) 105 second–1
(b) 205 second–1
(c) 95 second–1
(d) 100 second–1

A

Question 13. The total mechanical energy of a spring-mass system in simple harmonic motion is m 2A2 E = 1/2 mω2A2 . Suppose the oscillating particle is replaced by another particle of double the mass while the amplitude A remains the same. The new mechanical energy will
(a) become 2E
(b) become E/2
(c) become √2E
(d) remain E

D

Question 14. Two sources of sound placed close to each other, are emitting progressive waves given by y1 = 4sin600pt and y2 = 5sin608pt An observer located near these two sources of sound will hear
(a) 4 beats per second with intensity ratio 25 : 16 between waxing and waning.
(b) 8 beats per second with intensity ratio 25 : 16 between waxing and waning.
(c) 8 beats per second with intensity ratio 81 : 1 between waxing and waning.
(d) 4 beats per second with intensity ratio 81 : 1 between waxing and waning.

D

Question 15. For production of beats the two sources must have
(a) different frequencies and same amplitude
(b) different frequencies
(c) different frequencies, same amplitude and same phase
(d) different frequencies and same phase

B

Question 16. A source of frequency u gives 5 beats/second when sounded with a source of frequency 200 Hz. The second harmonic of frequency 2u of source gives 10 beats/second when sounded with a source of frequency 420 Hz. The value of u is
(a) 205 Hz
(b) 195 Hz
(c) 200 Hz
(d) 210 Hz.

A

Question 17. Wave has simple harmonic motion whose period is 4 seconds while another wave which also possesses simple harmonic motion has its period 3 seconds. If both are combined, then the resultant wave will have the period equal to
(a) 4 s
(b) 5 s
(c) 12 s
(d) 3 s

C

Question 18. An organ pipe open at one end is vibrating in first overtone and is in resonance with another pipe open at both ends and vibrating in third harmonic. The ratio of length of two pipes is
(a) 1 : 2
(b) 4 : 1
(c) 8 : 3
(d) 3 : 8

A

Question 19. Two waves of wavelengths 99 cm and 100 cm both travelling with velocity 396 m/s are made to interfere. The number of beats produced by them per second is
(a) 1
(b) 2
(c) 4
(d) 8

C

Question 20. A whistle of frequency 1000 Hz is sounded on a car travelling towards a cliff with velocity of 18 m s–1 normal to the cliff. If c = 330 m s–1, then the apparent frequency of the echo as heard by the car driver is nearly
(a) 1115 Hz
(b) 115 Hz
(c) 67 Hz
(d) 47.2 Hz

A

Question 21. When a sound wave of frequency 300 Hz passes through a medium, the maximum displacement of a particle of the medium is 0.1 cm. The maximum velocity of the particle is equal to
(a) 60p cms–1
(b) 30p cms–1
(c) 30 cms–1 30 cms-1
(d) 60 cms–1

A

Question 22. An organ pipe, open from both end produces 5 beats per second when vibrated with a source of frequency 200 Hz.  The second harmonic of the same pipes produces 10 beats per second with a source of frequency 420 Hz. The fundamental frequency of organ pipe is
(a) 195 Hz
(b) 205 Hz
(c) 190 Hz
(d) 210 Hz

B

Question 23. A progressive sound wave of frequency 500 Hz is travelling through air with a speed of 350 ms–1. A compression maximum appears at a place at a given instant. The minimum time interval after which the rarefraction maximum occurs at the same point, is
(a) 200 s
(b) 1/250s
(c) 1/500s
(d) 1/1000s

D

Question 24. A person carrying a whistle emitting continuously a note of 272 Hz is running towards a reflecting surface with a speed of 18 km h–1. The speed of sound in air is 345 m s–1. The number of beats heard by him is
(a) 4
(b) 6
(c) 8
(d) zero

C

Question 25. An engine running at speed /v10 sounds a whistle of frequency 600 Hz. A passenger in a train coming from the opposite side at speed V/15 experiences this whistle to be of frequency f. If v is speed of sound in air and there is no wind, f is near to
(a) 710 Hz
(b) 630 Hz
(c) 580 Hz
(d) 510 Hz

A

Question 26. A source of sound produces waves of wavelength 60 cm when it is stationary. If the speed of sound in air is 320 m s– 1 and source moves with speed 20 m s–1, the wavelength of sound in the forward direction will be nearest to
(a) 56 cm
(b) 60 cm
(c) 64 cm
(d) 68 cm

A

Question 27. A sonometer wire of length l vibrates in fundamental mode when excited by a tuning fork of frequency 416 Hz. If the length is doubled keeping other things same, the string will
(a) vibrate with a frequency of 416 Hz
(b) vibrate with a frequency of 208 Hz
(c) vibrate with a frequency of 832 Hz
(d) stop vibrating

A

Question 28. In the sonometer experiment, a tuning fork of frequency 256 Hz is in resonance with 0.4 m length of the wire when the iron load attached to free end of wire is 2 kg. If the load is immersed in water, the length of the wire in resonance would be (specific gravity of iron = 8)
(a) 0.37 m
(b) 0.43 m
(c) 0.31 m
(d) 0.2 m

A

Question 29. Two strings A and B, made of same material, are stretched by same tension. The radius of string A is double of radius of B. A transverse wave travels on A with speed vA and on B with speed vB. The ratio vA / vB is
(a) 1/2
(b) 2
(c) 1/4
(d) 4

A

Question 30. An organ pipe P1 closed at one end vibrating in its first overtone and another pipe P2 open at both ends vibrating in third overtone are in resonance with a given tuning fork.
The ratio of the length of P1 to that of P2 is
(a) 8/3
(b) 3/8
(c) 1/2
(d) 1/3

B

Question 31. Where should the two bridges be set in a 110cm long wire so that it is divided into three parts and the ratio of the frequencies are 3 : 2 : 1 ?
(a) 20cm from one end and 60cm from other end
(b) 30cm from one end and 70cm from other end
(c) 10cm from one end and 50cm from other end
(d) 50cm from one end and 40cm from other end

A

Question 32. A source X of unknown frequency produces 8 beats per second with a source of 250 Hz and 12 beats per second with a source of 270 Hz. The frequency of the source X is
(a) 242 Hz
(b) 258 Hz
(c) 282 Hz
(d) 262 Hz

B

Question 33. A tuning fork of freqqency 512 Hz makes 4 beats per second with the vibrating string of a piano. The beat frequency decreases to 2 beats per sec when the tension in the piano string is slightly increased. The frequency of the piano string before increasing the tension was
(a) 510 Hz
(b) 514 Hz
(c) 516 Hz
(d) 508 Hz

D

Question 34. A car is moving towards a high cliff. The car driver sounds a horn of frequency f. The reflected sound heard by the driver has as frequency 2f. If v be the velocity of sound, then the velocity of the car, in the same velocity units, will be
(a) v /2
(b) v /Ö2
(c) v /3
(d) v /4

C

Question 35. Two vibrating tuning forks produce progressive waves given by Y1 = 4 sin 500 pt and Y2 = 2 sin 506 pt. Number of beats produced per minute is
(a) 360
(b) 180
(c) 60
(d) 3

B

Question 36. Two identical piano wires kept under the same tension T have a fundamental frequency of 600 Hz. The fractional increase in the tension of one of the wires which will lead to occurrence of 6 beats/s when both the wires oscillate together would be
(a) 0.02
(b) 0.03
(c) 0.04
(d) 0.01

A

Question 3. Velocity of sound waves in air is 330 m/s. For a particular sound wave in air, a path difference of 40 cm is equivalent to phase difference of 1.6p. The frequency of this wave is
(a) 165 Hz
(b) 150 Hz
(c) 660 Hz
(d) 330 Hz

C

Question 4. Two waves are represented by the equations
y1 = a sin (wt + kx + 0.57) m and y2 = a cos (wt + kx) m, where x is in meter and t in sec. The phase difference between them is

A

Question 5. Sound waves travel at 350 m/s through a warm air and at 3500 m/s through brass. The wavelength of a 700 Hz acoustic wave as it enters brass from warm air
(a) decreases by a factor 10
(b) increases by a factor 20
(c) increases by a factor 10
(d) decreases by a factor 20

C

Question 6. Speed of sound wave in air
(a) is independent of temperature
(b) increases with pressure
(c) increases with increase in humidity
(d) decreases with increase in humidity

C

Question 7. Two sources of sound placed close to each other are emitting progressive waves given by y1 = 4 sin 600 pt and
y2 = 5 sin 608 pt. An observer located near these two sources of sound will hear
(a) 4 beats per second with intensity ratio 25 : 16 between waxing and waning.
(b) 8 beats per second with intensity ratio 25 : 16 between waxing and waning
(c) 8 beats per second with intensity ratio 81 : 1 between waxing and waning
(d) 4 beats per second with intensity ratio 81 : 1 between waxing and waning

D

Question 8. Water waves produced by a motorboat sailing in water are
(a) neither longitudinal nor transverse
(b) both longitudinal and transverse
(c) only longitudinal
(d) only transverse

B

Question 9. Which of the following statements are true for wave motion?
(a) Mechanical transverse waves can propagate through all mediums
(b) Longitudinal waves can propagate through solids only
(c) Mechanical transverse waves can propagate through solids only
(d) Longitudinal waves can propagate through vacuum

C

Question 10. Change in temperature of the medium changes
(a) frequency of sound waves
(b) amplitude of sound waves
(c) wavelength of sound waves
(d) loudness of sound waves

C

Question 11. With propagation of longitudinal waves through a medium, the quantity transmitted is
(a) matter
(b) energy
(c) energy and matter
(d) energy, matter and momentum

B

Question 12. A source of unknown frequency gives 4 beats/s, when sounded with a source of known frequency 250 Hz. The second harmonic of the source of unknown frequency gives five beats per second, when sounded with a source of frequency 513 Hz. The unknown frequency is
(a) 246 Hz
(b) 240 Hz
(c) 260 Hz
(d) 254 Hz

D

Question 13. Two sources P and Q produce notes of frequency 660 Hz each. A listener moves from P to Q with a speed of 1 ms–1. If the speed of sound is 330 m/s, then the number of beats heard by the listener per second will be
(a) zero
(b) 4
(c) 8
(d) 2

B

Question 14. A sound wave is passing through air column in the form of compression and rarefaction. In consecutive compressions and rarefactions,
(a) density remains constant
(b) Boyle’s law is obeyed
(c) bulk modulus of air oscillates
(d) there is no transfer of heat

D

Question 15. If we study the vibration of a pipe open at both ends, then which of the following statements is not true ?
(a) Odd harmonics of the fundamental frequency will be generated
(b) All harmonics of the fundamental frequency will be generated
(c) Pressure change will be maximum at both ends (d) Antinode will be at open end

C

Question 16. 110cm is equal to the second overtone of an organ pipe open at both the ends. The length of organ pipe open at both the ends is
(a) 100 cm
(b) 120 cm
(c) 140 cm
(d) 80 cm

A

Question 17. A string is stretched between two fixed points separated by 75.0 cm. It is observed to have resonant frequencies of 420 Hz and 315 Hz. There are no other resonant frequencies between these two. The lowest resonant frequency for this string is :
(a) 205 Hz
(b) 10.5 Hz
(c) 105 Hz
(d) 155 Hz

C

Question 18. The number of possible natural oscillation of air column in a pipe closed at one end of length 85 cm whose frequencies lie below 1250 Hz are : (velocity of sound = 340 ms–1)
(a) 4
(b) 5
(c) 7
(d) 6

D

Question 19. A speeding motorcyclist sees trafic jam ahead of him. He slows down to 36 km/hour. He finds that traffic has eased and a car moving ahead of him at 18 km/hour is honking at a frequency of 1392 Hz. If the speeds of sound is 343 m/s, the frequency of the honk as heard by him will be :
(a) 1332 Hz
(b) 1372 Hz
(c) 1412 Hz
(d) 1464 Hz

C

Question 20. The two nearest harmonics of a tube closed at one end and open at other end are 220 Hz and 260 Hz. What is the fundamental frequency of the system?
(a) 20 Hz
(b) 30 Hz
(c) 40 Hz
(d) 10 Hz

A

Question 21. Two cars moving in opposite directions approach each other with speed of 22 m/s and 16.5 m/s respectively. The driver of the first car blows a horn having a frequency 400 Hz. The frequency heard by the driver of the second car is [velocity of sound 340 m/s] :-
(a) 361 Hz
(b) 411 Hz
(c) 448 Hz
(d) 350 Hz

C

Question 22. A siren emitting a sound of frequency 800 Hz moves away from an observer towards a cliff at a speed of 15ms–1. Then, the frequency of sound that the observer hears in the echo reflected from the cliff is :
(Take velocity of sound in air = 330 ms–1)
(a) 765 Hz
(b) 800 Hz
(c) 838 Hz
(b) 885 Hz

C

Question 23. An air column, closed at one end and open at the other, resonates with a tuning fork when the smallest length of the column is 50 cm. The next larger length of the column resonating with the same tuning fork is :
(a) 66.7 cm
(b) 100 cm
(c) 150 cm
(d) 200 cm

C

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