Sound Waves Questions and Answers

A string of length 50 cm and mass 2 5 g is fixed at both ends A pipe closed at one end has a length of 85 cm When the string vibrates in its second overtone and the air column in the pipe in its first overtone they produce a beats frequency of 6 Hz It is also observed that decreasing the tension in the string decreases beats frequency Neglect the end correction in the pipe and velocity of sound in air is 340 m s then the tension in the string is A 72 N C 26 N B 52 N D 18 N

1 For a particular tube there are four of six harmoni frequencies below 1000 Hz are 300 Hz 600 Hz 750 Hz and 900 Hz Find the frequencies missing from list 1 100 200 Hz 3 150 450 Hz 2 150 400 Hz 4 450 800 Hz

A car is moving with a constant velocity 10 m s towards a stationary wall An observer in between the car and the wall is moving with a constant velocity 2 m s towards the stationary wall The car blows a horn of frequency 320 Hz The velocity of sound in air is 330 m s The beats frequency received by the observer is A 2 Hz C 6 Hz B 4 Hz D 8 Hz Vs 10 m s V 2 m s rough

0 An observer is moving towards a stationary sound source If speed of observer is increased by 20 then percentage change in the wavelength of sound as observed by observer is Ich tech for saft frit af 20 da dech ari fed caft 1 10 rada 2 20 3 25 4 zero

20x10 4 Two different instruments say guitar ar harmonium playing same music the sound appears different though they pla same frequency because they have different loudness 2 they are played by different person and hence difference in tuning they have different quality 4 they create different pitch x

At t 0 a sound source S and observers 0 O2 are placed as shown S is moving with speed V and 0 and O2 are moving with speed Vo At any later instant let f and f represent apparent frequencies of sound observed by 0 and O respectively The ratio f f is Note V and Vo are less than speed of sound in this medium AV 0 0 2 1 Question Type Single Correct Type 2 3 zero V 2 0 S 1 2 0 0 between 0 and 1

A man standing midway between two cliffs claps his hand and starts hearing a series of echoes of interval of 1 s The speed of sound in air is 340 m s the distance between the cliffs is 340 m 680 m 1020 m 170 m

A sonometer wire of length is in resonance with a frequency 250 Hz If th length of wire is increased to then 2 beats per second are heard The ratio o lengths of wire will be 1 2 A B 124 125 C 2 1

5 In which of the following case Interference of two waves is not observed 1 Point Superposing waves having same frequency but different amplitude Superposing waves having same

Solvelancer TestFgure shows sound source of frequency 140Hz and a car blowing horn continuously with same frequency as of sound source Find number of beats heard by boy on bike when he is ut A and car is at B Take speed o sound 360m a Solvencer Test a 4 25Hz b 6 5Hz c 2 73Ha

8 A closed organ pipe and an open pipe of the same length produce 4 beats when they are set into vibrations simultaneously If the length of each of them were twice their initial lengths the number of beats produced will be 1 2 2 4 3 1 4 8 frequer under increas the occ wires w 1 0 01

A plane travelling at 256 m s uses ultrasoni c sound generator that generates a wave of wavelength 1 6 cm and frequency 22 kHz to measure the altitude It receives the reflecte d signal 8 seconds later Find the altitude

A tuning fork A produces 4 beats s with another tuning fork B of frequency 320 Hz On filling one of the prongs of A 4 beats s are again heard when sounded with the same fork B Then the frequency of the fork A before filing is A 328 Hz B 316 Hz C 324 Hz D 320 Hz Correct Answer Your Answer

41 Two different sound sources Sand S have freqencies in the ratio 1 2 Source S is approaching towards observer and S receding from same observer Speeds of both S and S are V each and speed of sound air is 330 m s If no beats are heard by the observer then the value of V is 2 1 50 m s 2 75 m s 3 110 m s 4 125m s

A source of frequency f gives 5 beats sec when sounded with a source of frequency 200 Hz The second harmonic of source of frequency f gives 10 beats sec when sounded with a source of frequency 420 Hz The value of fis 195 Hz 410 Hz 205 Hz 390 Hz

A truck blowing horn of frequency 500 Hz travels towards a vertical mountain and driver hears echo of frequency 600Hz If velocity of sound in air is 340m s then speed of truck is 1 31 m s 2 41m s 3 51m s 4 21m s

8 Two aeroplanes A and B are moving away from one another with a speed of 720 kmph 45 The frequency of the whistle emitted by A is 1100 Hz The apparent frequency of the whistle as heard by the passenger of the aeroplane B is velocity of sound in air is 350 ms 1 300Hz 2 400Hz 3 500Hz 4 600H 1 A to ec ai 1

he 44 of he y a source of sound is travelling towards stationary observer The freqency of sound heard by the observer is 25 more than that of the actual freqency if speed of sound is V that of the source is 1 V 5 2 V 4 3 V 3 4 V 2

ds ta nd in 20 In the figure the intensity of waves arriving at D from two coherent sources s and s2 is Io The wavelength of the wave is 4 m Resultant intensity at D will be a 4 S10 3m S2 h lo 4m 21 D

21 A tuning fork of 512 Hz is used to produce resonance in a resonance tube experiment The level of water at first resonance is 30 7 cm and at second resonance is 63 2 cm The error in calculating velocity of sound is Speed of sound in air 330 m s a 204 1 cm s c 58 cm s b 110 cm s d 280 cm s

2 In Sor vibrating length is O O O O poir directly proportional to the tension in the wire directly proportional to the square root of tension in the wire inversely proportional to the tension in the wire inversely proportional to the square root of tension in the wire

50 Velocity of sound waves in air is 330 m sec For a particular sound in air a path difference of 40 cm is equivalent to a phase difference of 1 6 The frequency of this wave is af 330 m sec 40 cm 1 6 CR 1 165 Hz 2 150 Hz 3 660 Hz 4 330 Hz

A rod is clamped at both of its ends and stationary longitudinal waves are produced in it In first experiment the rod has a total of 4 nodes with amplitude of each anti node to be 1 mm In other experiment the rod has a total of 6 nodes with amplitude of each anti node to be 2mm The energy of vibrations in the rod in two cases is E and E2 respectively E Write value of E2 Question Type Numerical Type

What is the fundamental frequency of a musical instrument if the frequency of the 5th overtone is 240 Hz Instruction Write only number Do not write unit

d 1 1 3 A motor car is moving towards a vertical wall The driver observes that the frequency of the sound of his horn changes from 440 Hz to 480 Hz when he hears the reflected sound from the wall If the velocity of sound is 330 m s what is the speed of the car

n the figure shown S and S are two identical coherent sources of sound separated by d A receiver moves along line XY which is parallel to S S to detect intensity of sound at various points on the line Distance of line XY from S S is D d Distance of first intensity maxima on ine XY measured from O is y Find percentage change in value of y if the temperature of air increases by 1 If your answer is X fill value of 6X X

string 5 beats per second is heard If tension in the string is slightly increased then beats with the same tuning fork become 3 beats per second The frequency of stretched wire before increasing the tension is Frequency of tuning fork is 256 Hz 1 261 Hz 2 256 Hz 3 251 Hz 4 259 Hz

The speed of sound in oxygen is 315 ms At the same temperature its speed in a mixture of oxygen and nitrogen in the ratio 1 4 by volume is given 10 3 162 1 320 ms 1 1 3 332 ms 2 310 ms 1 4 340 ms 1

TT A man while sitting on an oscillating swing whistles at a frequency 1000 Hz The swing is oscillating with an amplitude radian about the mean position in a vertical plane Man is sitting over the swing which is at a distance of 2m from the point of suspension of the swing Another man standing just infront of the mean position of the swing hears the whistle The maximum frequency heard by the man standing in front of the swing is Speed of sound in air 332 m s Question Type Single Correct Type 1 2 3 1016 Hz 1007 Hz 1003 Hz

When open pipe is closed from one end then third overtone of closed pipe is higher in frequency by 150 Hz than second overtone of open pipe The fundamental frequency of end pipe will be open MHT CET 2016 A 75 Hz 150 Hz C 225 Hz T1 B LIDT D 300 Hz

20 The siren of a police car emits a pure tone at a frequency of 1125 Hz Find the frequency that you would perceive in your car under the following circumstances a Your car at rest police car moving toward you at 29 m s b Police car at rest your car moving toward it at 29 m s c You and the police car moving toward one another at 14 5 m s d You moving at 9 m s police car chasing behind you at 38 m s

30 In a quink tube experiment a tuning fork of frequency 300 Hz is vibrated at one end It is observed that intensity decreases from maximum to 50 of its maximum value as tube is moved by 6 25 cm Velocity of sound is m s

A sound source S moves with speed of 20 m s with respect to the medium There are two detectors A B located as shown in figure If wavelength emitted by source are in the range of 20 to 50 cm the choose CORRECT statement s 20m s A A wavelength detected by A may be 20 cm 30 cm 50 cm B A wavelength detected by A may be 19 cm 30 cm 41 cm C A wavelength detected by B may be 20 cm 30 cm 50 cm D A wavelength detected by B may be 22 cm 51 cm 53 cm

The diagram above shows the basic idea behind a disk siren It consists of a disk in which there are 16 equally spaced holes all at the same distance from its axle When a jet of air is directed at the holes and the disc is rotated at a particular constant rate the frequency of the note produced is 320 Hz When a disk containing 24 holes is rotated at 4 3 times the rate then frequency of note produced is 320 n Hz Find the value of n Air

A wall is moving with velocity u and a source of sound frequency f moves with velocity same direction as shown Assuming that the sound travels with a speed of 10u pick the right option or options A wavelength of incident sound is C wavelength of reflected sound is st u 2 S 19u 2f 18 B frequency of the incident sound is 19 D frequency of the reflected sound is 12f 19

A man is riding a vehicle towards a vertical cliff with a velocity of 36 km h He fires a gunshot and hears its echo after 4 sec The speed of sound in air is 320 m s i ii The distance between the cliff and the position where he shot the gun is A 640 m B 680 m C 620 m D 660 m If the speed of the vehicle increases by 4 times then the time taken to hear the echo is A 11 3 seconds B 10 3 seconds C 3 seconds D None of the above 4

A small source S of mass m starts moving with velocity 40 m s towards a detector D of same mass m on a frictionless surface AB as shown in the figure The frequency received by the detector as a function of time in the time interval 0 t 16 s is Assume all collisions to be elastic Take v 340 m s A C f 4 8 8 t 12 12 A 16 16 t 0 S 160m D B D 160m f f 4 B 8 8 t 12 12 16 16

A pipe open at both ends has a fundamental frequency f in air The pipe is dipped vertically in water so that 3 4th of it is in water The fundamental frequency of the air column is now 01 20 O 3f

One end of 12 0 m long rubber tube with a total mass of 0 9 kg is fastened to a fixed support A cord attached to the other end passes over a pulley and supports an object with a mass of 5 0 kg The tube is struck by a transverse blow at lower end Find the time required for the pulse to reach the other end of the rubber tube g 9 8 m s 12 m m Cord Rubber tube

Question No 25 A stationary source is emitting sound at a fixed frequency fo which is reflected by two cars approaching the source The difference between the frequencies of sound reflected from the cars is 1 2 of fo What is the difference in the speeds of the cars in km per hour The cars are moving at constant speeds much smaller than the speed of sound which is 330 m s Options

I wo friends start cycling around a circular track radius R in the same sense starting from the same point with angular speed W and 2w The slower one is continuously singing with his vocal cord frequency fo Rw 1 of Vsound Then regarding the frequency of song heard by the faster one Answer A Your Attempt B C Rate this question Correct answer Observed minimum frequency 98 9940 Observed minimum frequency 97f 99 0 Observed maximum frequency 101001201000 0 The spectrum of frequencies

1 consider two progressive wave trains of different wavelength and frequency but the same amplitude A propagated in the ve direction The wave amplitude equuations are y x t 10sin 2x 3 y2 x t 10sin 3x 4 i find resultant wave ii determine the group velocity and the phase velocity

84 Which of the following stat 3702675675 The problem of having to describe waves arises in fields like acoustics electromagnetics and fluid dynamics Jean d Alembert discovered the three

Two sirens situated one kilometre apart are producing sound of frequency 330 Hz An observer starts moving from one siren to the other with a speed of 2 m s If the speed of sound be 330 m s what will be the beat frequency heard by the observer Question Type Single Correct Type 1 2 3 8 4 6

A loudspeaker L is placed in the hall with two doors D and D open to the playground as shown below The distance between D and D is 74 25 m The loudspeaker L is equidistant from D and D Monotonic sound waves are emitted from the loudspeaker and it is found that at both points P Q sound intensities are minimum Distance of point P from D is 6m The line joining D P and Q is perpendicular to the line joining D and D No other minimum intensity locations can be found between PQ and beyond Q along the PQ line The wavelength in metre of the sound wave generated by the loudspeaker is L Hall D

An open organ pipe of radius 1 cm is vibrating in it s 1 overtone Here origin is at left end of the pipe The x coordinate of pressure node can be CALO6cm B 0 6 cm C 100 6 cm D 100 cm

A loudspeaker which emits sound of frequency 1000 Hz is placed several metres from a plane reflecting wall A in a large chamber containing a gas A small microphone M detects a series of low and high intensity signals as it moves along the line joining the loudspeaker B and the wall loudspeaker B MO S A If the microphone detects tenth low intensity signals while moving through a distance S of 2 m what is the speed of sound in the chamber A 110 m s C 330 m s B 220 m s D 421 m s

A source of sound gives five beats per second when sounded with another source of frequency 100s The second harmonic of the source together with a source of frequency 205s gives five beats per second What is the frequency of the source

1 3 a and d 4 All are correct Three observers A B and C are listening to a 31 moving source of sound The diagram below shows the location of the wavecrests of the moving source with respect to the three stationary observers Which of the following is true 1 The wavefronts move faster at C than at A and B 2 The frequency of the sound is highest at A 3 The frequency of the sound is highest at B 4 The frequency of the sound is highest at C The diagram below shows the horizontal forces 32 3 a d 4 fra fag ABC fara a fer des saati wave crests fefa 1 B fafter t 2 A 3 Bet 4 C effa ate 20 0 kg fa

so the magnification is given by m 200 3 200 1 25 get the magnifying power comes out to be m 2 n 28 A string is stretched between fixed points separated by 75 cm It is observed to have resonant frequencies of 420 Hz and 315 Hz There are no other resonant frequencies between these two Then the lowest resonant frequency for this string is ption 1 D 5 Hz ption 2 D5 Hz ption 3 05 Hz 10 02 1 2 otion 4