Sound Waves Questions and Answers

Two sound waves having time periods 0 01000 s and 0 00926 s respectively If the waves have same amplitudes and superpose travelling in the same direction then find the beat frequency 02 04 O O 8 6 2 poi

180 If the length of string of a sonometer wire is shortened by 75 and the tension is increased by 44 then the percentage by which resonating frequency is changed Unchanged 60 20 380

frozen It is given Latent heat of vaporization of water at 0 C 21 10 J kg and latent heat of freezing of water 3 36 105J kg The maximum percentage amount of water that will be solidified in this manner will be A source of sound with natural frequency f moves uniformly along a straight line separated from a stationary observer by a distance e perpendicular distance The velocity of source is half of velocity of sound Find the frequency in Hz of sound received by the observer at the moment when the source gets closest to him Take f 250 00 Hz The friction coefficient between the horizontal surface and each of the block shown

Zero Marks 0 If none of the option is selected Negative Marks 1 If wrong option is selected A train is moving at a speed of v towards the railwayman next to the rails The train whistles for a time of T How long does the railwayman hear the whistle The speed of sound is c 330 m s v 108 km hour 30 m s T 3 s the train does no reach the railwayman until the end of the whistle O 1 732 S O 2 727 S 4 O3 212 S

39 Two monochromatic light waves are travelling with same frequency and constant phase different If both waves interfere then a there is a gain of energy b there is a loss of energy c the energy is redistributed and the distribution remains constant in time d the energy is redistributed and the distribution changes with time

Two coherent sources of sound S and S2 produce sound waves of the same wavelength 1 m in phase S and S are placed 1 5 m apart see fig A listener located at L directly in front of S finds that the intensity is at a minimum when he is 2 m away from S The listener moves away from S keeping his distance from S fixed The adjacent maximum of intensity is observed when the listener is at a distance d from S Then d is S 1 5m 2m d 2m L ExamSide Com

The length of sonometer wire between two fixed ends is 100 cm Three bridges A B C are placed from left end so as to divide the wire into four segments whose fundamental frequencies are in ratio of 1 3 4 2 Then match the following List I P Position of A from left end is Q R Position of B from left end is Position of C from right end is S Separation between A C is A P 3 Q4 R 2 S 1 C P 2 Q3 R 1 S 4 List II 24 cm 28 cm 48 cm 64 cm 1 2 3 4 B P 1 Q 2 R 3 S4 D P 3 Q4 R 1 S 2

sity 24 If sound travels in air with the speed of 340 m s then number of tones present in an open organ pipe of length 2 m and its maximum frequency 1200 Hz are a 17 b 11 d 14 C 9

6 Two sound producing sources A and B are moving towards and away from a stationary observer with same speed respectively If frequency of sound produced by both sources are equal as 400 Hz then speed of sources approximately when observer detects 4 beats per second is Given speed of sound 340 m s a 1 7 m s b 3 4 m s c 2 4 m s d 1 m s

If the third harmonic vibration in an open air pipe equals the fifth harmonic of vibration in an air pipe closed at one end the possible values of the length of air column in the closed pipe and pipe end respectively corrections are 1 Question Type Single Correct Type 240 cm 120 cm 2 60 cm 72 cm 3 200 cm 120 cm open neglect 4 180 cm 150 cm

A train is approaching a stationary with sounding a whistle Then the observer hears the sound of observer 1 Same frequency 2 Slightly lower frequency 3 Slightly higher frequency 4 Same frequency but of different quality

Two persons P and are standing at a distance of 100 m from a high wall as shown in the figure When P gives a clap the time interval between the two direct and reflected sounds heard by Q is 0 2 s If the speed of sound is 340ms then the distance d between P and Q is Wall

Frequency of tuning fork A is 250 Hz It produces 4 beats sec with another tuning fork B When A is filed the beat frequency is 6 beats sec The frequency of B is A 264 Hz B C 254 Hz 250 Hz

A tuning fork vibrating with a sonometer wire of length 20 cm produces 5 beats per second The beat frequency does not change if the length of the wire is changed to 21 cm The frequency of the tuning fork must be A 200 Hz B 210 Hz c 205 Hz D 215 Hz

A man standing between two large parallel cliffs produces a sound He hears the first echo after 6 s and next echo 2 s later If speed of sound is 330 m s then the distance between the cliffs will be 561 m 1000 m O1400 m 2310 m

An observer is moving with a speed 30 m s towards a stationary source of sound of frequency 100 Hz The apparent frequency heard by the observer will be speed of sound 330 m s 109 Hz 112 Hz 91 Hz 86 Hz

A large cylindrical chamber has a massless piston fitted at the top An acoustic source is situated at the centre the bottom of the cylinder while an observer is situated at the bottom circumference inside the chamber The observer is moving directly towards the source with constant velocity and hears a frequency f 13 If the chamber were to be isobarically heated then the observed frequency will be A same as f C lower than f B higher than f D data insufficient

A source of frequency 1800 Hz is moving on line with speed 30 m s An observer is standing at a point far distant from the line The wavelength of sound received by the observer when the source is nearest to the observer is n 11 metres Find n speed of sound in air 330 m s source Se

2 The volume of a room is 1200m3 The wall area of the room is 220m3 The floor area is 120 m2 and the ceiling area is 120m2 The average absorption coefficient 1 for walls is 0 03 ii for the ceiling is 0 80 iii for the floor is 0 06 Calculate the average sound absorption coefficient and the reverberation time

Two boats are rowing on a pond in the same direction and with the same speed V Each boat sends through the water which is at rest a signal to the other The frequencies of the generated signals are the same 1 ii iii are correct 1 The time taken by the signals to travel from one boat to the other is different ii The wavelengths received by both the persons in the boats due to the other are different iii The beat frequencies received by both the persons are different iv The beat frequencies received by both the persons are same which may include zero also Choose the INCORRECT option s ii iii are correct iii is correct O i ii iv are correct V 00 V

A tuning fork of natural frequency 250 Hz starts to vibrate At the same time another tuning fork is also vibrating If the intensity of sound is found to reach a maximum value once in 5 seconds which of the following can be the natural frequency of the second tuning fork Choose the best options 250 5 Hz 250 2 Hz 249 8 Hz 250 Hz

A 3 6 m long vertical pipe is filled completely with a liquid A small hole is drilled at the base of the pip due to which liquids starts leaking out This pipe resonates with a tuning fork The first two resonance occur when height of water column is 3 22 m and 2 34 m respectively The area of cross section of pig is Answer A 25 cm B C Your Attempt D 100 cm 200 cm 400 cm Correct answer Rate this ques

Sound waves in air are always longitudinal because Question Type Single Correct Type 1 2 3 density of air is very small Air is a mixture of several gases Air does not have a modulus of rigidity 4 of the inherent characteristics of sound waves in air

A car blowing a horn of frequency 350 Hz is moving normally towards a wall with a speed of 5 m s The beat frequency heard by a person standing between the car and the wall is speed of sound in air 350 m s Question Type Single Correct Type 1 zero 2 3 5 Hz 3 5 Hz

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 10 25 pm

29 A test tube of length 1 and area of cross section A has some iron fillings of mass M The test tube floats normally in a liquid of density p with length x dipped in the liquid A disturbing force makes the tube oscillate in the liquid The time period of oscillation is given by neglect the mass of the test tube a 2n Mp Ag b 2 g c 2T g M Vg d 2

4 A pipe open at one end has length 0 8 m At the open end of the tube a string 0 5m long is vibrating in its 1st overtone and resonates with fundamental frequency of pipe If tension in the string is 50N the mass of string is speed of sound 320 m s 25 gram S Is X 1 X 2 X 3 4 15 gram 20 gram 10 gram

The frequencies of two forks are 256 and 256 05 Hz When sounded together after how much interval maximum sound will become half if the minimum intensity is zero A 10 sec 3 5 sec

23 The engine of a train sounds a whistle at frequency v The frequency heard by a passanger is If wind is blowing from passanger side to Train side A v v C 1 D v

383 49 Two identical flutes produce fundamental notes of frequency 300 Hz at 27 C If the temperature of the air in one of the flutes is increased to 31 C the number of beats heard per second will be a 3 c 1 b 2 d 4

When open pipe is closed from one end then thir overtone of closed pipe is higher in frequency by 150 Hz than second overtone of open pipe The fundamental frequency of open end pipe will be a 75 Hz c 225 Hz b 150 Hz d 300 Hz MHT CET the

1 c d 5 28 A long glass tube is held vertically in water A tuning fork is struck and held over the tube Strong resonances are observed at two successive lengths 0 50 m and 0 84 m above the surface of water If velocity of sound is 340 m s then the frequency of the tuning fork is a 128 Hz b 256 Hz d 500 Hz c 384 Hz 79 A particle executes SHM with an amplitude of

A closed organ pipe and an open organ pipe of sam length produce 2 beats sec when they are set int vibrations together in fundamental mode The lengt of open pipe is now halved and that of closed pipe doubled The number of beats produced will be c 8 b d 2

A source of sound of single frequency vo flies along a straight line which is at a finite distance from the observer Then t observer hears 0 a frequency vo at the instant when the source is nearest to him a frequency greater than vo at the instant when the source is nearest to him 0 a frequency vo at an instant later than the instant of nearest position of the source 0 the variation of frequency with time is linear

orbed by rotating co Two to the wheel 1 50 A car is initially at rest 330 m away from a stationan observer It begins to move towards the observer with an acceleration of 1 1 ms sounding its hom continuously 20 s later the driver stops sounding the horn The velocity of sound in air is 330 m The observer will hear the sound of the horn for a duration of a 20 s c 20 20 s b 21 s d 19 rau same p outside a 0 c 7 2 A ball viscou propor a 1 c A vess nitrog

V1 and 2 are the velocities of sound at the same temperature in two monoatomic gases of densities p and P2 respectively If P P2 then the ratio of velocities and 2 will be Option A B C 1 2 4 1 2 1 Rate this questio

An air column tube is filled with water A sound source is placed just above it which emits a constant frequency As you lower the level of the water you find resonance in the tube occurs at 7 05 cm 21 15 cm and at 35 25 cm as noted by an increase in the volume of the sound The first 3 resonant lengths are what is given If the temperature in the room in which you are doing your experiment is 20 0 C what is the frequency of the sound used

1m 1 m a c 7 A sound is moving towards a stationary listener with th of the speed of sound The ratio of apparent to 10 real frequency is 10 c b 2 m 2 m d 10 b d 10

a 2 89 There are 26 tuning forks arranged in the decreasing order of their frequencies Each tuning fork gives 3 beats with the next The first one is octave of the last What is the frequency of 18th tuning fork a 100 Hz b 99 Hz c 96 Hz d 103 Hz Twnturning forks of frequencies n and n produces

of 300 m s 93 A train standing at the outer signal of a railway station blows a whistle of frequency 400 Hz in still air The train begins to move with a speed of 30 m s towards the platform The frequency of the sound heard by an observer standing on the platform is Speed of sound in air 330 m s a 420 Hz b 430 Hz c 440 Hz d 450 Hz in 3 s when usly If one of elength of the d 1 99 m m pipe of same vibrating in

c 67 The frequency of tuning fork is 256 Hz It will not resonate with a fork of frequency a 786 Hz c 512 Hz b 738 Hz d 256 Hz

354 96 A train approaching a railway platform with a speed of 20 m s starts blowing the whistle Speed of sound in air is 340 m s If the frequency of the emitted 99 sound from the whistle is 640 Hz the frequency of sound as heard by person standing on the platform is a 600 Hz c 680 Hz b 640 Hz d 720 Hz

Two tuning forks A and B produce notes of frequencies 258 Hz and 262 Hz An unknown note wounded with A produces certain beats When the same note is sounded with R the beat frequency pets doubled The unknown frequency is 250 Hz b 252 Hz c 254 Hz d 256 Hr of frequency 512 Hz produces 5 92

a c 430 Hz 87 A sound wave travels with a velocity of 300 m s through a gas 9 beats are produced in 3 s when two waves pass through it simultaneously If one of the waves has 2 m wavelength the wavelength of the other wave is a 1 98 m b 2 04 m c 2 06 m d 1 99 m ning and an open organ pipe of same 93

a zero b 5 c 1 98 A source of sound producing wavelength 50 cm is moving away from a stationary observer with speed of sound Then what is the wavelength of sound received by the observer

c Third d Fourth tring 67 The frequency of tuning fork is 256 Hz It will not morts resonate with a fork of frequency and a 786 Hz c 512 Hz b 738 Hz d 256 Hz

78 A glass tube of 1 0 m length is filled with wa The water can be drained out slowly at the bottom of the tube If a vibrating tuning fork of frequency 500 Hz is brought at the upper end of the tube and the velocity of sound is 330 ms then the wo number of resonances obtained will be a 4 b 3 c 2 BEATS d 1

69 A pipe 17 cm long is closed at one end Which harmonic mode of the pipe resonates a 1 5kHz source Speed of sound in air 340 ms b Third d Seventh a First c Fifth

c 680 Hz d 720 Hz 97 An observer moves towards a stationary source of sound with a velocity one fifth of the velocity of sound The percentage change in the apparent frequency is a zero b 5 c 10 d 20

pets do a 250 Hz b A tuning fork A of frequency 512 Hz produces 5 beats per second when sounded with another tuning fork 8 of unknown frequency If B is loaded with wax the number of beats is again 5 per second The frequency of the tuning fork B before it was loaded is a 502 Hz b 507 Hz d 522 Hz c 517 H ar strings A and B are slightly out of tune and Hz When the tension B C D