Sound Waves Questions and Answers

PART I PHYSICS 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 O 195 Hz O205 Hz 190 Hz O examsnet com

A tuning fork is placed near a vibrating stretched wire If frequency of tuning fork is greater than frequency of stretched wire hen a boy standing near the two hears a beat frequency f List l List II P Q R S If tuning fork is loaded with wax If prongs of tuning fork are filed If tension in stretched wire is increased If tension in stretched wire is decreased 1 2 3 4 Beat frequency must increase Beat frequency must decrease Beat frequency may increase Beat frequency may decrease

2 21 An engine is approaching a cliff at a constant speed When it is at a distance of 0 9 km from cliff it sounds a whistle The echo of the no sound is heard by the driver after 5 seconds nos Velocity of sound in air is equal to 330 ms The speed of the engine is km h

24 180 A sound source emitting a sound of frequency 945 Hz is moving away from a man at rest towards a hill at a speed of 54 kmh The frequency of sound that the man hears in the echo reflected from the hill is Given speed of sound in air 330 ms 990 Hz 870 Hz 1320 Hz 850 Hz

The frequency of a turning fork A is 2 more than the frequency of a standard turning fork The frequency of another fork B is 3 less than th frequency of a standard turning fork If 6 beat s are heard when the two turning forks A and B are excited the frequency A is 120 Hz 122 4 Hz 116 4 Hz Marks 4 00 1 0 130 Hz

Single Correct A wave of frequency 500 Hz has a velocity of 350 m s The distance between two nearest point on the wave which are 60 out of phase with eac other will be around 70 cm 0 7 m 12 0 cm 120 0 cm A A Marks 4 00 1

A While performing resonance column experiment to measure the speed of sound a student gets the first resonance condition at a column length of 18 cm during winter Repeating the same experiment during summer she measures the column length to be x cm for the second resonance Then B C X 18 X 54 18 x 36 A 18 x 54 Marks 4 00 1 00

A sound wave of wavelength and angular frequency oo travels with a speed v in a medium of density 2n X be the propagation constant If p and A are the pressure amplitude and displacement amplitude respectively then the intensity of sound wave is Choose the INCORRECT option pand bulk modulus B Let k A I BkoA 2 2 mas B I vp 2B C I 3p 2pv p D 1 2 pB I

In figure 6 9 a microwave transmitter a height a above the water level of a wide lake transmits microwaves of wavelength towards a receiver on the opposite shore a distance x above the water level The microwaves reflecting from the water interfere with the microwaves arriving directly from the transmitter Assuming that the lake width D is much greater than a and x and that a at what values of x is the signal at the receiver maximum Figure 6 9 C

Fill in the blanks for Resonance tube i In resonance tube first resonanting length is 25 cm then its second resonanting length will be if e 0 11 1

10 A glass tube of 100 cm length is filled with water 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 in air is 330 m s then the total number of resonances obtained will be NCERT XI Pg 382 1 4 2 3 3 2 4 1 13 a string of length rigid support The point w to be plucked and touche r 1 Plucked at 2 Plucked at O FI 4 4 and to L and to

11 A tuning fork A of frequency 512 Hz produces 5 beats per second when sounded with another tuning fork B of unknown frequency If B is loaded with wax the number of beats is again 5 per second The frequency of fork B before it was loaded is NCERT XI Pg 384 1 507 Hz 2 502 Hz 3 517 Hz 4 522 Hz 12 The equation of a stationary wave along a N 1 1 20 4 Plucked at and t 14 An observer moves t source of sound with a the velocity of sour change in apparent fre XI Pg 386 1 0

1 L2 driven by a common oscillator and amplifier are arranged as shown The frequency of the oscillator is gradually increased from zero and the detector at D records a series of maxima and minima If the speed of sound is 330 m s then the frequency at which the first maximum is observed L 8 9 m is a 165 Hz c 495 Hz L 40 m b 330 Hz d 660 Hz

y 512 H2 sounded en unknown wax the cond The loaded is Pg 384 along a n by x and y paration ADLAL CAMERA L 4 Plucked at and touch at 2 3L 4 14 An observer moves towards a stationary source of sound with a velocity one fifth of the velocity of sound The percentage change in apparent frequency is NCERT XI Pg 386 1 0 2 5 3 10 4 20 15 A railway engine whistling at a constant frequency moves with a constant speed It goes past a stationary observer standing honide the railuou tranl TI 424 Hz 430 Hz 432 Hz 4 16 If a wave is incident on a su of the incident wave is reflec part is transmitted into the se then O any mecha is tr INCE her 1 Incident and refracted ansverse Snell s law of refraction edium whi 2 Incident and refracted he lowest oboy lows of refractio2021 07 31 00 04

organ Five beats are produced by simultaneously blowing two clos pipes of different lengths in their fundamental mode If the shorter organ pipe is 25 cm in length and speed of sound in air is 320 m s What is the length of other organ pipe O 25 4 cm O 27 2 cm O 19 6 cm O 32 5 cm

Five beats are produced by simultaneously blowing two closed organ pipes of different lengths in their fundamental mode If the shorter organ pipe is 25 cm in length and speed of sound in air is 320 m s What is the length of other organ pipe O 25 4 cm O 27 2 cm O 19 6 cm O 32 5 cm

Aclosed organ pipe of length Lis vibrating in its first overtone There is a point Qinside the pipe at a distance 7 L 9 from the open end The ratio of pressure amplitude at Qto the maximum pressure amplitude in the pipe is A 1 2 C 1 1 B 2 1 D 2 3

The relation between first resonance length 1 and second resonance length 12 of closed air column is ay may sila chale 11 auf Options O 1 21 O 1 31 O 21 O 31 1

Q56 Two radio stations broadcast their programs at the same amplitude A and at slightly different frequen cies w and w2 respectively where wi 10 Hz A detector receives the signals from the two stations simultaneously It can only detect signals of intensity 2A 1993 a Find the time interval between successive maxima of the intensity of the signal received by the detec tor b Find the time for which the detector remains idle in each cycle of the intensity of the signal

47 The figure below shows the displacement vs time plot of a particle undergoing simple harmonic motion The acceleration of the particle at time t sec would be A B C 3 16 D cm sec 3 32 3 16 3 32 cm sec cm sec cm sec y cm 1 4 8 12 t sec 16

9 4 YR 5 sin 4rt tan A light string is tied at one end to a fixed support and to a heavy string of equal length L at the other end A as shown in figure A block of mass M is tied to the free end of heavy string Mass per unit length of the strings are u and 16 and tension is T Find lowest positive value of frequency such that junction point A is a node 1 1 T LV 3 T UA 16 WI 4 M 5 T 2 24 la

Two sources of sound placed close to each other are emitting progressive waves given by y 4 sin 600nt and Y 5 sin 608 t An observer located near these two sources of sound will hear AIPMT 2012 1 8 beats per second with intensity ratio 81 1 between waxing and waning 2 4 beats per second with intensity ratio 81 1 between waxing and waning 3 4 beats per second with intensity ratio 25 16 between waxing and waning 4 8 beats per second with intensity ratio 25 16 hotwoon waxing and waning

If we study the vibration of a pipe open at both ends then the following statement is not true NEET 2013 1 Odd Odd harmonics of the fundamental frequency will be generated 2 All harmonics of the fundamental frequency will be generated 3 Pressure change will be maximum at both ends 4 Open end will be anti node

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 NEET 2016 1 200 cm 3 100 cm 2 66 7 cm 4 150 cm

A string is stretched between 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 Re AIPMT 2015 1 105 Hz 3 205 Hz 2 155 Hz 4 10 5 Hz

31 In a closed organ pipe of length 105 cm standing waves are set up corresponding to third overtone What distance from the closed end a pressure node is formed 1 5 cm 2 15 cm 3 25 cm 4 30 cm 3 1 15 1 15 5 w 27

A tuning fork of frequency 330 Hz resonates with an air column of length 120 cm in a cylindrical tube in the fundamental mode When water is slowly poured in it the minimum height of water required for observing resonance once again is velocity of sound 330 ms 1 75 cm 2 50 cr 3 30 cm 4 45 cm

iw 996hu 2 18 When a sound source of frequency n is approaching a stationary observer with velocity u than the apparent change in frequency is An and when the same source is receding with velocity u from the stationary observer than the apparent change in frequency is An Then W 1 An An 3 An An 2 An An 4 An An

2 Q 16 A long string having a cross sectional area 0 80 mm and density 12 5 g cm is subjected to a tension of 64 N along the x axis One end of the string is attached to a vibrator moving in transverse direction At t 0 the source is at maximum displacement y 1 cm Find the speed of wave travelling on the string 1 40 m s 2 80 m s 3 20 m s 4 100 m s

View in English Question No 41 A racing car moving towards a hill sounds its horn Driver of the car observes that the sound reflected from the hill has a pitch one octave higher than the actual sound of the horn If sound is travelling with velocity Vo then the car is moving with velocity

he correct answer given is option 4th But my answer Please explain the question and provide other solutio en the previous one 21 A person have a whistle emitting continuously a sound of frequency 660 Hz While producing this sound he is running towards a vertical wall with a speed of 5 m s If the speed of sound in air is 335 m s then number of beats heard by him will be 1 20 Hz 2 10 Hz 3 8 Hz 4 No beats will be heard

Which of the following statements are true for a stationary waves A Energy particle has a fixed amplitude which is different from the amplitude of material particle B All the particle cross their mean position at the same time C There is net transfer of energy across any plane There are same particles which are always at rest FOT

A person have a whistle emitting continuously a sound of frequency 660 Hz While producing this sound he is running towards a vertical wall with a speed of 5 m s If the speed of sound in air is 335 m s then number of beats heard by him will be 20 Hz 10 Hz 8 Hz No beats will be heard

At every instant the ratio of the magnitude of the electric field to the magnetic field for an electromagnetic wave in vacuum is equal to Question Type Single Correct Type 1 2 3 4 The speed of radiowaves The speed of y ray The speed of light All of the above

Two strings of the same material and same length are given equal tension If they are vibrating with fundamental fequencies 1600 Hz and 900 Hz then the ratio of their respective diameters is A 16 9 B 4 3 C 81 256

A source plays a tone with frequency fo 440 Hz What is the speed in m s of a car moving straight towards the source if the driver hears a frequency of 462 Hz Speed of sound in the air is v 340 ms the effects of the material of the car can be neglected Consider three particles with positive charges Q 1C Q 2C and Q 4C placed in vacuum C

PIPE TUBE WAVES The fundamental frequency in an open organ pi equal to the third harmonic of a closed organ If the length of the closed organ pipe is 20 cm length of the open organ pipe is b 8 cm a 13 2 cm d 16 cm c 12 5 cm

he ratio of intensities between two coherent sound sources is 9 1 If the intensity of louder source is 45 dB then calculate intensity in B at point where both the waves interfere constructively Use log 02 0 301 log 03 0 477

Fourty one forks are arranged such that each produces 5 beats per second when sounded with its near fork If frequency of first fork is half of the frequency of last fork then the frequencies of the first and last fork are respectively in Hz 200 400 105 210 240 480 100 200

In a resonance tube experiment the first resonance is obtained for 10 cm of air column and the second resonance is obtained for 32 cm The end correction for this apparatus is equal to 0 5 cm O 1 cm 1 5 cm 2 cm

33 A sinusoidal wave is travelling on a string If the frequency of the wave is 150 Hz and mass per unit length of the string is 0 2 g m The average power transmitted by this wave shown is 0 06 m 1 2 34 W 3 4 80 W 20 cm 2 3 84 W 4 6 25 W

Q No 18 A thermodynamic system undergoes cyclic process ABCDA as shown in fig The work done by the system in the cycle is P 3P 2P P Vo Correct Answer 4 Your Answer 1 Status incorrect B D 2V V POVO 2POVO Po Vo 2 Zero

Imagine a very thin uniform wire of length meter and total mass 1 gram Fix one end of the wire in the ceiling hang a large mass of 1 kg from the other end then pluck the wire at m from the top Assume that as the wire vibrates the large mass is not moving The lowest frequency heard is 100 Hz What is the length of the wire in meter You may ignore the effect of gravity on the mass of the string Correct answer 1

person blows into open end of a long pipe As a result a high pressure pulse of air travels down e pipe When this pulse reaches the other end of the pipe A A high pressure pulse starts travelling up the pipe if the other end of the pipe is open B A low pressure pulse starts travelling up the pipe if the other end of the pipe is open C A low pressure pulse starts travelling up the pipe if the other end of the pipe is closed D A high pressure pulse starts travelling up the pipe if the other end of the pipe is closed

A tuning fork is kept between two organ pipes A and B Organ pipe A is closed at one end and is of length 18 cm while organ pipe B is opened a both ends as shown in the figure If fourth over tone of pipe B and first overtone of pipe A are in resonance with tuning fork then the length of open organ pipe B is Y 60 cm 50 cm 40 cm O 30 cm

A closed organ pipe of length 28 cm closed at one end is found to be in resonance when a tuning for frequency 850 Hz is sounded near the open end If velocity of sound in air is 340 m s then the A end correction of the pipe is 1 cm B end correction of the pipe is 2 cm C air in the pipe is vibrating in fundamental mode D air in the pipe is vibrating in first overtone

Two cars A and B are moving in same direction such that A is behind B with same speed v and are blowing horn of frequency f If a cyclist is moving between two cars from B to A with speed y then the beat frequency observed by cyclist is v is velocity of sound in air Vo 2 fvo 1 2015 10 V 17 2vf 2 v v vo v ud V V 2 vf Vo V 2 v v Source

39 The intensity of sound during the festival season increased by 100 times This could imply a decibel level rise from a 20 to 120 dB c 100 to 10000 dB b 70 to 72 dB d 80 to 100 dB

A sound wave is travelling in a uniform pipe with gas of adiabatic exponenty If u is the particle velocity dP at any point in medium and c is the wave velocity then relative change in pressure while wave P passes through this point is aft in de A u u uzy gaz v fav e ain n ain xu faz yar ve era unifuras fada C B Y u C Y faci far dP u P

A point like sound source emits sound in all direction uniformly An observer who is at a distance of 50 m from the source detects sound of intensity 10 8 W m If the bulk modulus of air is 1 6 105 N m and velocity of sound is 340 m s Find pressure amplitude at the position of observer If your answer is x x 10 N m fill value of x