JEE Questions for Physics Waves Quiz 13 - MCQExams.com

If in an experiment for determination of velocity of sound by resonance tube method using a tuning fork of 512 Hz, first resonance was observed at 30.7 cm and second was obtained at 63.2 cm, then maximum possible error in velocity of sound is (consider actual speed of sound in air is 332 m/s)
  • 204 cm/sec
  • 110 cm/sec
  • 58 cm/sec
  • 80 cm/sec
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 frequency of source is
  • 195 Hz
  • 205 Hz
  • 190 Hz
  • 210 Hz
In one metre long open pipe what is the harmonic of resonance obtained with a tuning fork of frequency 480 Hz?
  • First
  • Second
  • Third
  • Fourth
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
  • 1 : 2
  • 4 : 1
  • 8 : 3
  • 3 : 8
In a resonance pipe the first and second resonances are obtained at depths 22.7 cm and 70.2 cm respectively. What will be the end correction?
  • 1.05 cm
  • 115.5 cm
  • 92.5 cm
  • 113.5 cm
An open tube is in resonance with string (frequency of vibration of tube is n0). If tube is dipped in water so that 75% of length of tube is inside water, then the ratio of the frequency of tube to string now will be
  • 1
  • 2

  • Physics-Waves-96723.png

  • Physics-Waves-96724.png
Two closed organ pipes A and B, have the same length. A is wider than B. They resonate in the fundamental mode at frequencies nA and nB respectively, then
  • nA = nB
  • nA > nB
  • nA < nB
  • Either (b) or (c) depending on the ratio of their diameters
In a closed organ pipe, the 1st resonance occurs at 50 cm. At what length of pipe, the 2nd resonance will occur?
  • 150 cm
  • 50 cm
  • 100 cm
  • 200 cm
If in a resonance tube a oil of density higher than that of water is used then the resonance frequency would be
  • Increased
  • Decreased
  • Slightly increased
  • Remain the same
The frequency of the fundamental note in an organ pipe is 240 Hz. On blowing air, frequencies 720 Hz and 1200 Hz are heard. This indicates that organ pipe is
  • A pipe closed at one end
  • A pipe open at both ends
  • Closed at both ends
  • Having holes like flute
If L1 and L2 are the lengths of the first and second resonating air columns in a resonance tube, then the wavelength of the note produced is

  • Physics-Waves-96728.png
  • 2)
    Physics-Waves-96729.png

  • Physics-Waves-96730.png

  • Physics-Waves-96731.png
A hollow cylinder with both sides open generates a frequency f in air. When the cylinder vertically immersed into water by half its length the frequency will be
  • f
  • 2f
  • f/2
  • f/4
If the velocity of sound in air is 350 m/s. Then the fundamental frequency of an open organ pipe of length 50 cm, will be
  • 350 Hz
  • 175 Hz
  • 900 Hz
  • 750 Hz
While measuring the speed of sound by performing a resonance column experiment, 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
  • x > 54
  • 54 > x > 36
  • 36 > x > 18
  • 18 > x
A glass tube of length 1.0 m is completely filled with water. A vibrating tuning fork of frequency 500 Hz is kept over the mouth of the tube and the water is drained out slowly at the bottom of the tube. If velocity of sound in air is 330 ms–1, then the total number of resonances that occur will be
  • 2
  • 3
  • 1
  • 5
A closed organ pipe and an open organ pipe of same length produce 2 beats/second while vibrating in their fundamental modes. The length of the open organ pipe is halved and that of closed pipe is doubled. Then, the number of beats produced per second while vibrating in the fundamental mode is
  • 2
  • 6
  • 8
  • 7
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
  • 60 cm
  • 50 cm
  • 45 cm
A cylindrical tube, open at both ends, has a fundamental frequency, f, in air. The tube is dipped vertically in water so that half of it is in water. The fundamental frequency of the air-column is now
  • f
  • f/2
  • 3f/4
  • 2f
A motor cycle starts from rest and accelerates along a straight path at 2 m/s2. At the starting point of the motor cycle there is a stationary electric siren. How far has the motor cycle gone when the driver hears the frequency of the siren at 94% of its value when the motor cycle was at rest ? (Speed of sound = 330 ms–1)
  • 49 m
  • 98 m
  • 147 m
  • 196 m
A band playing music at a frequency f is moving towards a wall at a speed vb. A motorist is following the band with a speed vm. If v be the speed of the sound, the expression for beat frequency heard by motorist is

  • Physics-Waves-96739.png
  • 2)
    Physics-Waves-96740.png

  • Physics-Waves-96741.png

  • Physics-Waves-96742.png
The frequency of a whistle of an engine is 600 cycles/sec is moving with the speed of 30 m/sec towards an observer. The apparent frequency will be (velocity of sound = 330 m/s)
  • 600 cps
  • 660 cps
  • 990 cps
  • 330 cps
A source of sound emits waves with frequency f Hz and speed V m/sec. Two observers move away from this source in opposite directions each with a speed 0.2 V relative to the source. The ratio of frequencies heard by the two observers will be
  • 3 : 2
  • 2 : 3
  • 1 : 1
  • 4 : 10
An observer moves towards a stationary source of sound of frequency n. The apparent frequency heard by him is 2n. If the velocity of sound in air is 332 m/sec, then the velocity of the observer is
  • 166 m/sec
  • 664 m/sec
  • 332 m/sec
  • 1328 m/sec
An observer is moving towards the stationary source of sound, then
  • Apparent frequency will be less than the real frequency
  • Apparent frequency will be greater than the real frequency
  • Apparent frequency will be equal to real frequency
  • Only the quality of sound will change
A person feels 2.5% difference of frequency of a motor-car horn. If the motor-car is moving to the person and the velocity of sound is 320 m/sec, then the velocity of car will be
  • 8 m/s (approx.)
  • 800 m/s
  • 7 m/s
  • 6 m/s (approx.)
Two passenger trains moving with a speed of 108 km/hour cross each other. One of them blows a whistle whose frequency is 750 Hz. If sound speed is 330 m/s, then passengers sitting in the other train, after trains cross each other will hear sound whose frequency will be
  • 900 Hz
  • 625 Hz
  • 750 Hz
  • 800 Hz
With what velocity an observer should move relative to a stationary source so that he hears a sound of double the frequency of source?
  • Velocity of sound towards the source
  • Velocity of sound away from the source
  • Half the velocity of sound towards the source
  • Double the velocity of sound towards the source
A source of sound emitting a note of frequency 200 Hz moves towards an observer with a velocity v equal to the velocity of sound. If the observer also moves away from the source with the same velocity v, the apparent frequency heard by the observer is
  • 50 Hz
  • 100 Hz
  • 150 Hz
  • 200 Hz
A source of sound is travelling towards a stationary observer. The frequency of sound heard by the observer is of three times the original frequency. The velocity of sound is v m/sec. The speed of source will be

  • Physics-Waves-96749.png
  • 2)
    Physics-Waves-96750.png

  • Physics-Waves-96751.png

  • Physics-Waves-96752.png
Two trains, each moving with a velocity of 30 ms–1 , cross each other. One of the train gives a whistle whose frequency is 600 Hz. If the speed of sound is 330 ms–1, the apparent frequency for passengers sitting in the other train before crossing would be
  • 600 Hz
  • 630 Hz
  • 920 Hz
  • 720 Hz
A train is moving at 30 ms–1 in still air. The frequency of the locomotive whistle is 500 Hz and the speed of sound is 345 ms–1. The apparent wavelength of sound in front of and behind the locomotive are respectively
  • 0.80 m, 0.63 m
  • 0.63 m, 0.80 m
  • 0.50 m, 0.85 m
  • 0.63 m, 0.75 m
The Doppler\'s effect is applicable for
  • Light waves
  • Sound waves
  • Space waves
  • Both (a) and (b)
A source of sound is moving with constant velocity of 20 m/s emitting a note of frequency 1000 Hz . The ratio of frequencies observed by a stationary observer while the source is approaching him and after it crosses him will be (Speed of sound v = 340 m/s)
  • 9 : 8
  • 8 : 9
  • 1 : 1
  • 9 : 10
A source and listener are both moving towards each other with speed v/10 , where v is the speed of sound. If the frequency of the note emitted by the source is f, the frequency heard by the listener would be nearly
  • 1.11f
  • 1.22f
  • f
  • 1.27f
A table is revolving on its axis at 5 revolutions per second. A sound source of frequency 1000 Hz is fixed on the table at 70 cm from the axis. The minimum frequency heard by a. listener standing at a distance from the table will be (speed of sound = 352 m/s)
  • 1000 Hz
  • 1066 Hz
  • 941 Hz
  • 352 Hz
A motor car blowing a horn of frequency 124 vib/sec moves with a velocity 72 km/hr towards a tall wall. The frequency of the reflected sound heard by the driver will be (velocity of sound in air is 330 m/s)
  • 109 vib/sec
  • 132 vib/sec
  • 140 vib/sec
  • 248 vib/sec
A source of sound of frequency n is moving towards a stationary observer with a speed S. If the speed of sound in air is V and the frequency heard by the observer is n1, the value of n1/n is
  • (V + S) / V
  • V / (V + S)
  • (V – S ) / V
  • V / (V – S)
A whistle giving out 450 Hz approaches a stationary observer at a speed of 33 m/s. The frequency heard by the observer in Hz is
  • 409
  • 429
  • 517
  • 500
An observer is moving away from source of sound of frequency 100 Hz. His speed is 33 m/s. If speed of sound is 330 m/s, then the observed frequency is
  • 90 Hz
  • 100 Hz
  • 91 Hz
  • 110 Hz
An observer standing at station observes frequency 219 Hz where a train approaches and 184 Hz when train goes away from him. If velocity of sound in air is 340 m/s, then velocity of train and actual frequency of whistle will be
  • 15.5 ms–1, 200 Hz
  • 19.5 ms–1, 205 Hz
  • 29.5 ms–1, 200 Hz
  • 32.5 ms–1, 205 Hz
A boy is walking away from a wall towards an observer at a speed of 1 metre/sec and blows a whistle whose frequency is 680 Hz. The number of beats heard by the observer per second is (Velocity of sound in air = 340 metres/sec)
  • Zero
  • 2
  • 8
  • 4
An observer moves towards a stationary source of sound, with a velocity one-fifth of the velocity of sound. What is the percentage increase in the apparent frequency?
  • 5%
  • 20%
  • Zero
  • 0.5%
The apparent frequency of a note, when a listener moves towards a stationary source, with velocity of 40 m/s is 200 Hz. When he moves away from the same source with the same speed, the apparent frequency of the same note is 160 Hz. The velocity of sound in air is (in m/s
  • 360
  • 330
  • 320
  • 340
A source of sound of frequency 256 Hz is moving rapidly towards a wall with a velocity of 5m/s. The speed of sound is 330 m/s. If the observer is between the wall and the source, then beats per second heard will be
  • 7.8 Hz
  • 7.7 Hz
  • 3.9 Hz
  • Zero
A man sitting in a moving train hears the whistle of the engine. The frequency of the whistle is 600 Hz
  • The apparent frequency as heard by him is smaller than 600 Hz
  • The apparent frequency is larger than 600 Hz
  • The frequency as heard by him is 600 Hz
  • None of the above
A whistle of frequency 500 Hz tied to the end of a string of length 1.2 m revolves at 400 rev/min. A listener standing some distance away in the plane of rotation of whistle hears frequencies in the range (speed of sound = 340 m/s)
  • 436 to 586
  • 426 to 574
  • 426 to 584
  • 436 to 674
A train moves towards a stationary observer with speed 34 m/s. The train sounds a whistle and its frequency registered by the observer is f1. If the train\'s speed is reduced to 17 m/s, the frequency registered is f2 . If the speed of sound is 340 m/s then the ratio f1 / f2 is
  • 18/19
  • 1/2
  • 2
  • 19/18
If source and observer both are relatively at rest and if speed of sound is increased then frequency heard by observer will
  • Increases
  • Decreases
  • Cannot be predicted
  • Will not change
A siren placed at a railway platform is emitting sound of frequency 5 kHz. A passenger sitting in a moving train A records a frequency of 5.5 kHz while the train approaches the siren. During his return journey in a different train B he records a frequency of 6.0 kHz while approaching the same siren. The ratio of the velocity of train B to that of train A is
  • 242/252
  • 2
  • 5/6
  • 11/6
A car sounding a horn of frequency 1000 Hz passes an observer. The ratio of frequencies of the horn noted by the observer before and after passing of the car is 11 : 9. If the speed of sound is v, the speed of the car is

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  • 2)
    Physics-Waves-96773.png

  • Physics-Waves-96774.png

  • Physics-Waves-96775.png
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