JEE Questions for Physics Waves Quiz 4 - MCQExams.com

A student performed the experiment to measure the speed of sound in air using resonance air-column method. Two resonances in the air column were obtained by lowering the water level. The resonance with the shorter air-column is the first resonance and that with the longer air-column is the second resonance. Then,
  • the intensity of the sound heard at the first resonance was more than that at the resonance
  • the prongs of the tuning fork were kept in a horizontal plane above the resonance tube
  • the amplitude of vibration of the ends of the prongs is typically around 1 cm
  • the length of the air-column at the first resonance was somewhat shorter than 1/4th of the wavelength of the sound in air
A cylindrical tube open at both ends, has a fundamental frequency fin air. The tube is dipped vertically in water, so that half of it is in water. The fundamental frequency of air column is now
  • f/2
  • f
  • 3f/4
  • 2f
Distance between nodes on a string is 5 cm. Velocity of transverse wave is 2 ms -1. Then the frequency is
  • 5 Hz
  • 10 Hz
  • 20 Hz
  • 15 Hz
A vibrating string of certain length 1 under a tension T resonates with a mode corresponding to the second overtone (third harmonic) of an air column of length 75 cm inside a tube closed at one end. The string also generates 4 beats/s, when excited along with a tuning fork of frequency n. Now, when the tension of the string is slightly increased the number of beats reduces 2 per second. Assuming the velocity of sound in air to be 340 ms -1, the frequency n of the tuning fork in Hz is
  • 344
  • 336
  • 117.3
  • 109.3
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
  • 18 > x
  • x > 54
  • 54 > x > 36
  • 36 > x >18
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
  • 4
The extension in a string obeying Hooke's law is x. The speed of sound in the stretched string is v. If the extension in the string is increased to 1.5 x, the speed of sound will be
  • 1.22 v
  • 0.61 v
  • 1.50 v
  • 0.75 v
An open organ pipe is closed suddenly with the result, that the second overtone of the closed pipe is found to be higher in frequency by 100 than the first overtone of the original pipe. Then, the fundamental frequency of the open pipe is
  • 200 s-1
  • 100 s-1
  • 300 s-1
  • 250 s-1
  • 150 s-1
n1 is the frequency of the pipe closed at one end and n2 is the frequency of the pipe open at both ends. If both are joined end to end, find the fundamental frequency of closed pipe, so formed

  • Physics-Waves-96112.png
  • 2)
    Physics-Waves-96113.png

  • Physics-Waves-96114.png

  • Physics-Waves-96115.png
Out of following incorrect statement is

  • Physics-Waves-96116.png
  • 2)
    Physics-Waves-96117.png
  • Quink' s tube experiment is related with beats
  • Echo phenomena is related with reflection of sound
If L1 and L2are the lengths of the first and second resonating air columns in a resonance tube, then the wavelength of the note produced is

  • Physics-Waves-96118.png
  • 2)
    Physics-Waves-96119.png

  • Physics-Waves-96120.png

  • Physics-Waves-96121.png
When the length of the vibrating segment of a sonometer wire is increased by 1%, the percentage change in its frequency is

  • Physics-Waves-96122.png
  • 2)
    Physics-Waves-96123.png
  • 1
  • 2
A standing wave having 3 nodes and 2 antinodes is formed between two atoms having a distance 1.21 A° between them. The wavelength of the standing wave is
  • 1.21 A°
  • 1.42 A°
  • 6.05 A°
  • 3.63 A°

Physics-Waves-96124.png

  • Physics-Waves-96125.png
  • 2)
    Physics-Waves-96126.png
  • 2

  • Physics-Waves-96127.png
A string fixed at both ends oscillates in 5 segments, length 10 m and velocity of wave is 20 ms -1. What is the frequency?
  • 5 Hz
  • 15 Hz
  • 10 Hz
  • 2 Hz
A segment of wire vibrates with a fundamental frequency of 450 Hz under a tension of 9 kg–wt. Then, tension at which the fundamental frequency of the same wire becomes 900 Hz is
  • 36 kg–wt
  • 27 kg–wt
  • 18 kg–wt
  • 72 kg–wt
A piston fitted in cylindrical pipe is pulled as shown in the figure. A tuning fork is sounded at open end and loudest sound is heard at open length 13 cm, 41 cm and 69 cm, the frequency of tuning fork if velocity of sound is 350 ms-1 , is
Physics-Waves-96129.png
  • 1250 Hz
  • 625 Hz
  • 417 Hz
  • 715 Hz
In Melde's experiment in the transverse mode, the frequency of the tuning fork and the frequency of the waves in the string are in the ratio
  • 2 : 1
  • 4 : 1
  • 1 : 1
  • 1 : 2
Two strings A and B of lengths, LA = 80cm and LB= x cm respectively are used separately in a sonometer. The ratio of their densities (d A / dB ) is 0.81. The diameter of B is one-half that of A. If the strings have the same tension and fundamental frequency, the value of x is
  • 33
  • 102
  • 144
  • 130
In an experiment with sonometer a tuning fork of frequency 256 Hz resonates with a length of 25 cm and another tuning fork resonates with a length of 16 cm. Tension of the string remaining constant. The frequency of the second tuning fork is
  • 163.84 Hz
  • 400 Hz
  • 320 Hz
  • 204.8 Hz
Two closed organ pipe A and B have the same length. A is wider than B. They resonate in the fundamental mode at frequencies vA and vB respectively, then
  • vA = vB
  • vA > vB
  • vA < vB
  • either (or (depending on the ratio of their diameters

Physics-Waves-96130.png
  • 3 cm
  • 4.5 cm
  • 6 cm
  • 1.5 cm
An open pipe is in resonance in 2nd harmonic with frequency v1. Now, one end of the tube is closed and frequency is increased to v2, such that the resonance again occurs in nth harmonic. Choose the correct option.

  • Physics-Waves-96131.png
  • 2)
    Physics-Waves-96132.png

  • Physics-Waves-96133.png

  • Physics-Waves-96134.png
A transverse wave propagating on a stretched string of linear density 3 × 10-4 kg – m-1 is represented by the equation, y = 0.2 sin (1.5x + 60t ), where, x is in metre and t is in second. The tension in the string (in newton) is
  • 0.24
  • 0.48
  • 1.20
  • 1.80
An open tube is in resonance with string. If tube is dipped in water, so that 75% of length of tube is inside water, then the ratio of the frequency (v0 ) of tube to string is
  • v0
  • 2v0

  • Physics-Waves-96135.png

  • Physics-Waves-96136.png
Two vehicles, each moving with speed u on the same horizontal straight road, are approaching each other. Wind blows along the road with velocity. One of these vehicles blows a whistle of frequency f1 . An observer in the other vehicle hears the frequency of the whistle to be f2. The speed of sound in still air is v. The correct statement(s) is (are)
  • If the wind blows from the observer to the source, f2 > f1
  • If the wind blows from the source to the observer, f2 = f1
  • If the wind blows from the observer to the source, f2 < f1
  • If the wind blows from the source to the observer, f2 < f1
A sound source is moving towards stationary listener with 1/10th of the speed of the sound. The ratio of apparent to real speed will be

  • Physics-Waves-96137.png
  • 2)
    Physics-Waves-96138.png

  • Physics-Waves-96139.png

  • Physics-Waves-96140.png
A stationary source is emitting sound at a fixed frequency f0, which is reflected by two cars approaching the source. The difference between the frequencies of sound reflected from the cars is 1.2% of f0. What is the difference in the speeds of the cars (in km per hour) to the nearest integer? The cars are moving at constant speeds much smaller than the speed of sound which is 330 ms -1.
  • 7.128 km/h
  • 7 km/h
  • 8.128 km/h
  • 9 km/h
The speed of sound in air is 340 m/s. The speed with which a source of sound should move towards a stationary observer, so that the apparent frequency becomes twice of the original is
  • 640 ms-1
  • 340 ms-1
  • 170 ms-1
  • 85 ms-1
A bat flies at a steady speed of 4 ms-1 emitting a sound of f = 90 × 103 Hz. It is flying horizontally towards a vertical wall. The frequency of the reflected sound as detected by the bat will be (take, velocity of sound in air as 330 ms -1 )
  • 88.1 × 103 Hz
  • 87.1 × 103 Hz
  • 92.1 × 103 Hz
  • 89.1 × 103 Hz
Two trains are moving towards each other with speeds of 20 m/s and 15 m/s relative to the ground. The first train sounds whistle of frequency 600 Hz, the frequency of the whistle heard by a passenger in the second train before the train meets is (take, the speed of sound in air is 340 m/s)
  • 600 Hz
  • 585 Hz
  • 645 Hz
  • 666 Hz
A motor cycle starts from rest and accelerates along a straight path at 2 ms -2 . 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? (take, speed of sound = 330 ms -1)
  • 49 m
  • 98 m
  • 147 m
  • 196 m
With what velocity should an observer approach stationary sound source, so that the apparent frequency of sound should appear double the actual frequency? (v is the velocity of sound)

  • Physics-Waves-96142.png
  • 3v
  • 2v
  • v
A bus is moving with a velocity of 5 ms -1 towards a huge wall. The driver sounds a horn of frequency 165 Hz. If the speed of sound in air is 335 ms -1, the number of beats heard per second by a passenger inside the bus will be
  • 3
  • 4
  • 5
  • 6
  • 7
When sound is produced in an aeroplane moving with a velocity of 200 ms -1 horizontal, its echo is heard after 10 √5s. If velocity of sound in air is 300 ms -1, the elevation of aircraft is
  • 250 m
  • 2)
    Physics-Waves-96143.png
  • 12.50 m
  • 2500 m
A car moving with a velocity of 36 kmh -1 crosses a siren of frequency 500 Hz. The apparent frequency of siren after passing it will be
  • 520 Hz
  • 485 Hz
  • 540 Hz
  • 460 Hz
If a source emitting waves of frequency v moves towards an observer with a velocity v/4 and the observer moves away from the source with a velocity v/ 6, the apparent frequency as heard by the apparent frequency as heard by the observer will be (v = velocity of sound)

  • Physics-Waves-96146.png
  • 2)
    Physics-Waves-96147.png

  • Physics-Waves-96148.png

  • Physics-Waves-96149.png
An engine moving towards a wall with a velocity 50 ms -1 , emits a note of 1.2 kHz. Speed of sound in air is 350 ms -1. The frequency of the note after reflection from the wall as heard by the driver of the engine is
  • 2.4 kHz
  • 0.24 kHz
  • 1.6 kHz
  • 1.2 kHz
A sounding source of frequency 500 Hz moves towards a stationary observer with a velocity 30 ms -1. If the velocity of sound in air is 330 ms -1, find the frequency heard by the observer.
  • 500 Hz
  • 550 Hz
  • 355 Hz
  • 55.5 Hz
A whistle of frequency 540 Hz rotates in a horizontal circle of radius 2 mat an angular speed of15 rads -1. The highest frequency heard by a listener at rest with respect to the centre of circle
(velocity of sound in air = 330 ms -1)
  • 590 Hz
  • 594 Hz
  • 598 Hz
  • 602 Hz
A racing car moving towards a cliff sounds its horn. The driver observes that the sound reflected from the cliff has a pitch one octave higher than the actual sound of the horn. If v is the velocity of sound, the velocity of the car is

  • Physics-Waves-96151.png
  • 2)
    Physics-Waves-96152.png

  • Physics-Waves-96153.png

  • Physics-Waves-96154.png
A whistle producing sound waves of frequency 9500 Hz above is approaching a stationary person with speed v ms -1. The velocity of sound in air is 300 ms -1. If the person can hear frequency upto a maximum of 10000 Hz, the maximum value of v upto which he can hear the whistle is
  • 15√2 ms-1
  • 15/√2 ms-1
  • 15 ms-1
  • 30 ms-1
The apparent frequency of the whistle of an engine changes in the ratio 9 : 8 as the engine passes a stationary observer. If the velocity of the sound is 340 ms -1, then the velocity of the engine is
  • 40 ms -1
  • 20 ms -1
  • 340 ms -1
  • 180 ms -1
  • 50 ms -1
A train moves towards a stationary observer with speed 34 ms -1. The train sounds a whistle and its frequency registered by the observer is v1. If the train's speed is reduced to 17 ms -1, the frequency registered is v2. If the speed of sound is 340 ms -1, then the ratio v1/v2 is
  • 2
  • 2)
    Physics-Waves-96155.png

  • Physics-Waves-96156.png

  • Physics-Waves-96157.png
The difference between the apparent frequency of a source of sound as perceived by the observer during its approach and recession is 2% of the frequency of the source. If the speed of sound in air is 300 ms -1, the velocity of the source
  • 1.5 ms -1
  • 12 ms -1
  • 6 ms -1
  • 3 ms -1
An observer is standing 500 m away from a vertical hill. Starting between the observer and the hill, a police van having a siren of frequency 1000 Hz, moves towards the hill with a uniform speed. If the frequency of the sound heard directly from the siren is 970 Hz, the frequency of the sound heard after reflection from the hill (in Hz) is about, (velocity of sound = 330 ms -1)
  • 1042
  • 1032
  • 1022
  • 1012
The apparent frequency of a note is 200 Hz, when a listener is moving with a velocity of 40 ms -1 towards a stationary source. 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 in ms -1 overlapping
  • 340
  • 330
  • 360
  • 320
A vehicle sounding a whistle of frequency 256 Hz is moving on a straight road, towards a hill with a velocity of 10 ms-11. The number of beats per second observed by a person travelling in the vehicle is
(velocity of sound = 330 ms-1)
  • zero
  • 10
  • 14
  • 16
Of the following, the equation of plane progressive wave is
  • y = r sin ωt
  • y = r sin (ωt – kx)

  • Physics-Waves-96159.png

  • Physics-Waves-96160.png
A stone is dropped into a well. If the depth of water below the top be h and velocity of sound in air be v, then the time after which splash of sound is heard is

  • Physics-Waves-96161.png
  • 2)
    Physics-Waves-96162.png

  • Physics-Waves-96163.png

  • Physics-Waves-96164.png
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