JEE Questions for Physics Waves Quiz 17 - MCQExams.com

The number of beats produced per second by two vibrations: x1 = x0 sin 646 πt and x2 = x0 sin 652 πt is
  • 2
  • 3
  • 4
  • 6
A glass tube 1.5 m long and open at both ends, is immersed vertically in a water tank completely. A tuning fork of 660 Hz is vibrated and kept at the upper end of the tube and the tube is gradually raised out of water. The total number of resonances heard before the tube comes out of water, taking velocity of sound air 330 m/sec is
  • 12
  • 6
  • 8
  • 4
If the speed of a wave doubles as it passes from shallow water into deeper water, its wavelength will
  • Unchanged
  • Halved
  • Doubled
  • Quadrupled
A man standing between two parallel hills, claps his hand and hears successive echoes at regular intervals of 1s. If velocity of sound is 340ms–1, then the distance between the hills is
  • 100 m
  • 170 m
  • 510 m
  • 340 m
A source of sound placed at the open end of a resonance column sends an acoustic wave of pressure amplitude inside the tube. If the atmospheric pressure ρA is ρo, then the ratio of maximum and minimum pressure at the dosed end of the tube will be

  • Physics-Waves-97017.png
  • 2)
    Physics-Waves-97018.png

  • Physics-Waves-97019.png

  • Physics-Waves-97020.png
The length of two open organ pipes are 1 and (l +∆l) respectively. Neglecting end correction, the frequency of beats between them will be approximately (Here v is the speed of sound)

  • Physics-Waves-97022.png
  • 2)
    Physics-Waves-97023.png

  • Physics-Waves-97024.png

  • Physics-Waves-97025.png
The fundamental note produced by a closed organ pipe is of frequencyf. The fundamental note produced by an open organ pipe of same length will be of frequency
  • f/2
  • f
  • 2f
  • 4f
An organ pipe P1 closed at one end vibrating in its first overtone and another pipe P2 open at both ends vibrating in its third overtone are in resonance with a given tuning fork. The ratio of lengths of P1 and P2 is
  • 1 : 2
  • 1 : 3
  • 3 : 8
  • 3 : 4
A resonance air column of length 20 cm resonates with a tuning fork of frequency 250 Hz. The speed of sound in air is
  • 300 m/s
  • 200 m/s
  • 150 m/s
  • 75 m/s
A cylindrical tube, open at both ends, has a fundamental frequency fo in air. The tube is dipped vertically into water such that half of its length is inside water. The fundamental frequency of the air column now is
  • 3f/4
  • fo
  • fo /2
  • 2fo
If the length of a closed organ pipe is 1.5 m and velocity of sound is 330 m/s, then the frequency for the second note is
  • 220 Hz
  • 165 Hz
  • 110 Hz
  • 55 Hz
Two closed organ pipes, when sounded simultaneously gave 4 beats per sec. If longer pipe has a length of 1m. Then length of shorter pipe will be, (v = 300 m/s)
  • 185.5 cm
  • 94.9 cm
  • 90 cm
  • 80 cm
A closed organ pipe and an open organ pipe are tuned to the same fundamental frequency. What is the ratio of lengths?
  • 1 : 2
  • 2 : 1
  • 2 : 3
  • 4 : 3
Find the fundamental frequency of closed pipe, if the length of the air column is 42 m. (speed of sound in air = 332 m/sec)
  • 2 Hz
  • 4 Hz
  • 7 Hz
  • 9 Hz
The frequency of fundamental tone in an open organ pipe of length 0.48 m is 320 Hz. Speed of sound is 320 m/sec. Frequency of fundamental tone in closed organ pipe will be
  • 153.8 Hz
  • 160.0 Hz
  • 320.0 Hz
  • 143.2 Hz
If fundamental frequency of closed pipe is 50 Hz then frequency of 2nd overtone is
  • 100 Hz
  • 50 Hz
  • 250 Hz
  • 150 Hz
Two open organ pipes of length 25 cm and 25.5 cm produce 10 beat/sec. The velocity of sound will be
  • 350 m/s
  • None of these
  • 255 m/s
  • 250 m/s
What is minimum length of a tube, open at both ends, that resonates with tuning fork of frequency 350 Hz? [velocity of sound in air = 350 m/s]
  • 50 cm
  • 100 cm
  • 75 cm
  • 25 cm
Two open organ pipes give 4 beats/sec when sounded together in their fundamental nodes. If the length of the pipe are 100 cm and 102.5 cm respectively, then the velocity of sound is
  • 496 m/s
  • 328 m/s
  • 240 m/s
  • 160 m/s
An open pipe is suddenly closed at one end with the result that the frequency of third harmonic of the closed pipe is found to be higher by 100 Hz, then the fundamental frequency of open pipe is
  • 480 Hz
  • 300 Hz
  • 240 Hz
  • 200 Hz
Tube A has both ends open while tube B has one end closed, otherwise they are identical. The ratio of fundamental frequency of tube A and B is
  • 1 : 2
  • 1 : 4
  • 2 : 1
  • 4 : 1
If the temperature increases, then what happens to the frequency of the sound produced by the organ pipe
  • Increases
  • Decreases
  • Unchanged
  • Not definite
Apparatus used to find out the velocity of sound in gas is
  • Melde's apparatus
  • Kundt's tube
  • Quincke's tube
  • None of these
The stationary wave y = 2a sin kx cos wt in a closed organ pipe is the result of the superposition of y y = a sin (ω t – kx) and
  • y = – a cos (ω t + kx)
  • y = – a sin (ω t + kx)
  • y = a sin (ω t + kx)
  • y = a cos (ω t + kx)
Fundamental frequency of pipe is 100 Hz and other two frequencies are 300 Hz and 500 Hz then
  • Pipe is open at both the ends
  • Pipe is closed at both the ends
  • One end open and another end is closed
  • None of the above
An open pipe of length 33 cm resonates with frequency of 100 Hz. If the speed of sound is 330 m/s, then this frequency is
  • Fundamental frequency of the pipe
  • Third harmonic of the pipe
  • Second harmonic of the pipe
  • Fourth harmonic of the pipe
In a resonance tube the first resonance with a tuning fork occurs at 16 cm and second at 49 cm. If the velocity of sound is 330 m/s, the frequency of tuning fork is
  • 500
  • 300
  • 330
  • 165
Two closed organ pipes of length 100 cm and 101 cm produce 16 beats in 20 sec. When each pipe is sounded in its fundamental mode calculate the velocity of sound
  • 303 ms-1
  • 332 ms-1
  • 323.2 ms-1
  • 300 ms-1
Two closed organ pipes A and B, have the same length. A is wider than B. They resonate in the fundamental mode at frequencies n A and n B respectively, then
  • n A = n B
  • n A > n B
  • n A < n B
  • Either (b) or (c) depending on the ratio of their diameters
An organ pipe P closed at one end vibrates in its first harmonic. Another organ pipe Q open at both ends vibrates in its third harmonic. When both are in resonance with a tuning fork, the ratio of the length of P to that of Q is
  • 1/2
  • 1/4
  • 1/6
  • 1/8
Air is blown at the mouth of an open tube of length 25 cm and diameter 2 cm. If the velocity of sound in air is 330 ms–1, then emitted frequencies are (in Hz)
  • 660,1320, 2640
  • 660,1000, 3300
  • 302,664,1320
  • 330,990,1690
Doppler shift in frequency does not depend upon
  • The frequency of the wave produced
  • The velocity of the source
  • The velocity of the observer
  • Distance from the source to the listener
A band playing music at a frequency f is moving towards a wall at a speed v b . A motorist is following the band with a speed v m . If v be the speed of the sound, the expression for beat frequency heard by motorist is

  • Physics-Waves-97069.png
  • 2)
    Physics-Waves-97070.png

  • Physics-Waves-97071.png

  • Physics-Waves-97072.png
The source producing sound and an observer both are moving along the direction of propagation of sound waves. If the respective velocities of sound, source and an observer are v, vs and vo, then the apparent frequency heard by the observer will be (n = frequency of sound)

  • Physics-Waves-97075.png
  • 2)
    Physics-Waves-97076.png

  • Physics-Waves-97077.png

  • Physics-Waves-97078.png
A whistle sends out 256 waves in a second. If the whistle approaches the observer with velocity 1/3 of the velocity of sound in air, the number of waves per second the observer will receive
  • 384
  • 192
  • 300
  • 200
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 sources A and B are sending notes of frequency 680 Hz. A listener moves from A and B with a constant velocity u. If the speed of sound in air is 340 ms–1, what must be the value of u so that he hears 10 beats per second?
  • 2.0 ms–1
  • 2.5 ms–1
  • 3.0 ms–1
  • 3.5 ms–1
A sound source is moving towards a stationary observer with 1/10 of the speed of sound. The ratio of apparent to real frequency is
  • 10/9
  • 11/10
  • (11/10)2
  • (9/10)2
Suppose that the speed of sound in air at a given temperature is 400 m/sec. An engine blows a whistle at 1200 Hz frequency. It is approaching an observer at the speed of 100 m/sec. What is the apparent frequency as heard by the observer?
  • 600 Hz
  • 1200 Hz
  • 1500 Hz
  • 1600 Hz
A source of sound S is moving with a velocity 50 m/s towards a stationary observer. The observer measures the frequency of the source as 1000 Hz. What will be the apparent frequency of the source when it is moving away from the observer after crossing him? The velocity of sound in the medium is 350 m/s
  • 750 Hz
  • 857 Hz
  • 1143 Hz
  • 1333 Hz
A source and listener are both moving towards each other with speed v/100 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 train approaches a stationary observer, the velocity of train being 1/20 of the velocity of sound. A sharp blast is blown with the whistle of the engine at equal intervals of a second. The interval between the successive blasts as heard by the observer is

  • Physics-Waves-97097.png
  • 2)
    Physics-Waves-97098.png

  • Physics-Waves-97099.png

  • Physics-Waves-97100.png
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 n19 the value of n1/n is
  • (V + S)/V
  • V/ (V + S)
  • (V - S)/V
  • V / (V - S)
A vehicle with a horn of frequency n is moving with a velocity of 30 m/s in a direction perpendicular to the straight line joining the observer and the vehicle. The observer perceives the sound to have a frequency n + n1. Then (if the sound velocity in air is 300 mis)
  • n1 = 1.0 n
  • n1 = 0
  • n1 = 0.1n
  • n1 = – 0.1n
The driver of a car travelling with speed 30 metres per second towards a hill sounds a horn of frequency 600 Hz. If the velocity of sound in air is 330 metres per second, the frequency of the reflected sound as heard by the driver is
  • 720 Hz
  • 555.5 Hz
  • 550 Hz
  • 500 Hz
Two sirens situated one kilometer 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 observe
  • 8
  • 4
  • 6
  • 1
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 500 Hz is moving towards an observer with velocity 30 m/s. The speed of sound is 330 m/s. The frequency heard by the observer will be
  • 550 Hz
  • 458.3 Hz
  • 530 Hz
  • 545.5 Hz
A source of sound of frequency 90 vibrations/ sec is approaching a stationary observer with a speed equal to 1/10 the speed of sound. What will be the frequency heard by the observer?
  • 80 vibrations/sec
  • 90 vibrations/sec
  • 100 vibrations/sec
  • 120 vibrations/sec
A source and an observer move away from each other with a velocity of 10 m/s with respect to ground. If the observer finds the frequency of sound coming from the source as 1950 Hz, then actual frequency of the source is (velocity of sound in air = 340 m/s)
  • 1950 Hz
  • 2068 Hz
  • 2132 Hz
  • 2486 Hz
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