JEE Questions for Physics Waves Quiz 7 - MCQExams.com

A wave travelling along a string is described by y = 0.005 Sin (40x – 2t) in SI units. The wavelength and frequency of the wave are………
  • (π/; 0.12 Hz
  • (π/m; 0.24 Hz
  • (π/m; 0.48 Hz
  • (π/m; 0.32 Hz
Two sitar strings A and B playing the note “Dha” are slightly out of time and produce beats of frequency 5 hz. The tension of the string B is slightly increased and the beat frequency is found to decrease to 3 hz. What is the original frequency of B if the frequency of A is 427 hz?
  • 432
  • 422
  • 437
  • 417
A rocket is moving at a speed of 130 m/s towards a stationary target. While moving, it emits a wave of frequency 800 Hz. Calculate the frequency of the sound as detected by the target. ( Speed of wave = 330 m/s)
  • 1320 Hz
  • 2540 Hz
  • 1270 Hz
  • 660 Hz
Length of a steel wire is 11 m and its mass is 2.2 kg. What should be the tension in the wire so that the speed of a transverse wave in it is equal to the speed of sound in dry air at 20o C temperature?
  • 2.31 × 104 N
  • 2.25 × 104 N
  • 2.06 × 104 N
  • 2.56 × 104 N
A wire stretched between two rigid supports vibrates with a frequency of 45 Hz. If the mass of the wire is 3.5 × 10–2 kg and its linear mass density is 4.0 × 10–2 kg/m, what will be the tension in the wire ?
  • 212 N
  • 236 N
  • 248 N
  • 254 N
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
A tuning fork arrangement produces 4 beats/second with one fork of frequency 288 Hz. A little wax is applied on the unknown fork and it then produces 2 beats/s. The frequency of the unknown fork is ……….Hz.
  • 286
  • 292
  • 294
  • 288
When temperature increases, the frequency of a tuning fork…….
  • Increases
  • Decreases
  • remains same
  • Increases or decreases depending on the material
A tuning fork of known frequency 256 Hz makes 5 beats per second with the vibrating string of a piano. The beats frequency decreases to 2 beats/s when the tension in the piano string is slightly increased. The frequency of the piano string before increase in the tension was ……..Hz.
  • 256 + 2
  • 256 – 2
  • 256 – 5
  • 256 + 5
Angle between wave velocity and particle velocity of a longitudinal wave is
  • 90°
  • 60°
  • 0°
  • 120°
An observer moves towards a stationary source of sound with a velocity one – fifth the velocity of sound. What is the percentage increase in the apparent frequency?
  • 5 %
  • 20 %
  • Zero
  • 0.5 %
The speed of sound in Oxygen ( O2) at a certain temperature is 460 m/s. The speed of sound in helium at the same temperature will be …….…….ms–1 . (Assume both gases to be ideal)
  • 330
  • 460
  • 5002
  • None of these
In a longitudinal wave, pressure variation and displacement variation are………
  • In phase
  • 90o out of phase
  • 45o out of phase
  • 180o out of phase
A tuning fork of frequency 480 Hz produces 10 beats/s when sounded with a vibrating sonometer string. What must have been the frequency of the string if a slight increase in tension produces fewer beats per second than before?
  • 480 Hz
  • 490 Hz
  • 460 Hz
  • 470 Hz
Which of the following functions represents a wave?

  • Physics-Waves-96356.png
  • 2)
    Physics-Waves-96357.png

  • Physics-Waves-96358.png

  • Physics-Waves-96359.png
Two sound waves are represented by y = aSin(ωt - kx) and y = aCos(ωt - kx). The phase difference between the waves in water is ……..

  • Physics-Waves-96360.png
  • 2)
    Physics-Waves-96361.png

  • Physics-Waves-96362.png

  • Physics-Waves-96363.png
A string of linear density 0.2 kg/m is stretched with a force of 500 N. A transverse wave of length 4.0 m and amplitude 1/l meter is travelling along the string. The speed of the wave is …….. m/s.
  • 50
  • 62.5
  • 2500
  • 12.5
Two wires made up of same material are of equal lengths but their radii are in the ratio 1 : 2. On stretching each of these two strings by the same tension, the ratio between their fundamental frequency is ……..
  • 1 : 2
  • 2 : 1
  • 1 : 4
  • 4 : 1
The tension in a wire is decreased by 19%, then the percentage decrease in frequency will be ………
  • 19%
  • 10%
  • 0.19%
  • None of these
An open organ pipe has fundamental frequency 100 Hz. What frequency will be produced if its one end is closed?
  • 100, 200, 300, ….
  • 50, 150, 250….
  • 50, 100, 200, 300…
  • 50, 100, 150, 200,…..
A closed organ pipe has fundamental frequency 100 Hz. What frequencies will be produced if its other end is also opened?
  • 200, 400, 600, 800,…..
  • 200, 300, 400, 500, …..
  • 100, 300, 500, 700,……
  • 100, 200, 300, 400, …….
A column of air of length 50 cm resonates with a stretched string of length 40 cm. The length of the same air column which will resonate with 60 cm of the same string at the same tension is ……..
  • 100 cm
  • 75 cm
  • 50 cm
  • 25 cm
Two forks A and B when sounded together produce 4 beats/s. The fork A is in unison with 30 cm length of a sonometer wire and B is in unison with 25 cm length of the same wire at the same tension. The frequencies of the fork are …….
  • 24 Hz, 28 Hz
  • 20 Hz, 24 Hz
  • 16 Hz , 20 Hz
  • 26 Hz, 30 Hz
A tuning fork of frequency 200 Hz is in unison with a sonometer wire. The number of beats heard per second when the tension is increased by 1 % is …….
  • 1
  • 2
  • 4
  • 0.5
A bus is moving with a velocity of 5 m/s towards a huge wall. The driver sounds a horn of frequency 165 Hz. If the speed of sound in air is 335 m/s, the number of beats heard per second by the passengers in the bus will be …….
  • 3
  • 4
  • 5
  • 6
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). If the sound velocity in air is 300 m/s, then……
  • n1 = 10 n
  • n1 = 0
  • n1 = 0.1 n
  • n1 = –0.1n
In a sine wave, position of different particles at time t = 0 is shown in figure. The equation for this wave travelling along the positive x – direction can be …….
Physics-Waves-96372.png
  • y = Asin ( ω t – kx )
  • y = Acos (kx – ω t)
  • y = Acos( ω t – kx )
  • y = Asin(kx – ω t)
Which of the following changes at an antinode in a stationary wave?
  • Density only
  • Pressure only
  • Both pressure and density
  • Neither pressure nor density
In brass, the velocity of a longitudinal wave is 100 times the velocity of a transverse wave. If Y = 1 × 1011 N/m2, then stress in the wire is …………
  • 1 × 1013 N/m2
  • 1 × 109 N/m2
  • 1 × 1011 N/m2
  • 1 × 107 N/m2
A sonometer wire supports a 4 kg load and vibrates in fundamental mode with a tuning fork of frequency 416 Hz. The length of the wire between the bridges is now doubled. In order to maintain fundamental mode, the load should be changed to …….
  • 1 Kg
  • 2 kg
  • 8 kg
  • 16 kg
The frequency of tuning fork A is 2% more than the frequency of a standard fork. Frequency of tuning fork B is 3% less than the frequency of the standard fork. If 6 beats per second are heard when the two forks A and B are excited, then frequency of A is …… Hz.
  • 120
  • 122.4
  • 116.4
  • 130
Fundamental frequency of a sonometer wire is n. If the length and diameter of the wire are doubled keeping the tension same, the new fundamental frequency is ………

  • Physics-Waves-96377.png
  • 2)
    Physics-Waves-96378.png

  • Physics-Waves-96379.png

  • Physics-Waves-96380.png
A car blowing its horn at 480 Hz moves towards a high wall at a speed of 20 m/s. If the speed of sound is 340 m/s, the frequency of the reflected sound heard by the driver sitting in the car will be closest to ……..Hz.
  • 540
  • 524
  • 568
  • 480
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/2
  • f
  • 3f/4
  • 2f
A wave travelling along the x-axis is described by the equation y(x,t) = 0.005 Cos (ax - at). If the wavelength and the time period of the wave are 0.08 m and 2.0 s respectively, then a and a in appropriate units are ………

  • Physics-Waves-96384.png
  • 2)
    Physics-Waves-96385.png

  • Physics-Waves-96386.png

  • Physics-Waves-96387.png
A wave travelling along a string is described by the equation y = A Sin (at – kx). The maximum particle velocity is ………..
  • Aα
  • α/k
  • dα/dk
  • x
A string is stretched between fixed points separated by 75 cm. It is observed to have a resonant frequencies of 420 Hz and 315 Hz. There are other resonant frequencies between these two. Then the lowest frequency for this string is ……..Hz.
  • 1.05
  • 1050
  • 10.5
  • 105
Two tuning forks P and Q when set vibrating gives 4 beats/second. If the prong of fork P is filed, the beats are reduced to 2/s. What is the frequency of P, if that of Q is 250 Hz?
  • 246 Hz
  • 250 Hz
  • 254 Hz
  • 252 Hz
A stationary wave of frequency 200 hz are formed in air. If the velocity of the wave is 360 m/s, the shortest distance between two antinodes is …….m
  • 1.8
  • 3.6
  • 0.9
  • 0.45
A tuning fork produces 8 beats per second with both 80 cm and 70 cm of stretched wire of a sonometer. Frequency of the fork is …….Hz.
  • 120
  • 128
  • 112
  • 240
Statement – 1: Two waves moving in a uniform string having uniform tension cannot have different velocities.
Statement – 2 : Elastic and inertial properties of string are same for all waves in same string. Moreover speed of wave in a string depends on its elastic and inertial properties only.
  • Statement – 1 is true, statement- 2 is true; statement-2 is the correct explanation of statement – 1 .
  • Statement – 1 is true, statement- 2 is true but statement-2 is not the correct explanation of statement – 1 .
  • Statement – 1 is true, statement- 2 is false
  • Statement – 1 is false, statement- 2 is true
Statement – 1: When a sound source moves towards observer, then frequency of sound increases.
Statement – 2 : Wavelength of sound in a medium moving towards the observer decreases
  • Statement – 1 is true, statement- 2 is true; statement-2 is the correct explanation of statement – 1 .
  • Statement – 1 is true, statement- 2 is true but statement-2 is not the correct explanation of statement – 1 .
  • Statement – 1 is true, statement- 2 is false
  • Statement – 1 is false, statement- 2 is true
Statement – 1: Newton’s equation for speed of sound was found wrong because he assumed the process to be isothermal.
Statement – 2 : When sound propagates, the compression\'s and rarefaction happen so rapidly that there is not enough time for heat to be distributed.
  • Statement – 1 is true, statement- 2 is true; statement-2 is the correct explanation of statement – 1 .
  • Statement – 1 is true, statement- 2 is true but statement-2 is not the correct explanation of statement – 1 .
  • Statement – 1 is true, statement- 2 is false
  • Statement – 1 is false, statement- 2 is true
Statement – 1 : When pressure in a gas changes, velocity of sound in gas may change.
Statement – 2 : Velocity of sound is directly proportional to square root of pressure.
  • Statement – 1 is true, statement- 2 is true; statement-2 is the correct explanation of statement – 1 .
  • Statement – 1 is true, statement- 2 is true but statement-2 is not the correct explanation of statement – 1 .
  • Statement – 1 is true, statement- 2 is false
  • Statement – 1 is false, statement- 2 is true
Statement – 1 : If wave enters from one medium to another medium then sum of amplitudes of reflected wave and transmitted wave is equal to the amplitude of incident wave.
Statement – 2 : If wave enters from one medium to another medium some part of energy is transmitted and rest of the energy is reflected back.
  • Statement – 1 is true, statement- 2 is true; statement-2 is the correct explanation of statement – 1 .
  • Statement – 1 is true, statement- 2 is true but statement-2 is not the correct explanation of statement – 1 .
  • Statement – 1 is true, statement- 2 is false
  • Statement – 1 is false, statement- 2 is true
A string 25 cm long and having a mass of 2.5 g is under tension. A pipe closed at one end is 40 cm long. When the string is set vibrating in its first overtone and the air in the pipe in its fundamental frequency, 8 beats per second is heard. It is observed that decreasing the tension in the string decreases the beat frequency. The speed of sound in air is 320 ms – 1 .
The frequency of the fundamental mode of the closed pipe is ….. Hz
  • 100
  • 200
  • 300
  • 400
A string 25 cm long and having a mass of 2.5 g is under tension. A pipe closed at one end is 40 cm long. When the string is set vibrating in its first overtone and the air in the pipe in its fundamental frequency, 8 beats per second is heard. It is observed that decreasing the tension in the string decreases the beat frequency. The speed of sound in air is 320 ms– 1.
The frequency of the string vibrating in its 1st overtone is …… Hz
  • 92
  • 108
  • 192
  • 208
string 25 cm long and having a mass of 2.5 g is under tension. A pipe closed at one end is 40 cm long. When the string is set vibrating in its first overtone and the air in the pipe in its fundamental frequency, 8 beats per second is heard. It is observed that decreasing the tension in the string decreases the beat frequency. The speed of sound in air is 320 ms– 1.
The tension in the string is very nearly equal to ……
  • 25N
  • 27 N
  • 28 N
  • 30N
Standing waves are produced by the superposition of two waves y1 = 0.05 Sin(3πt – 2x) and y2 = 0.05 Sin(3πt + 2x) where x and y are in meters and t is in seconds.
The speed ( in ms– 1 ) of each wave is ……
  • 1.5
  • 3.0
  • 3π/2
  • 3π
Standing waves are produced by the superposition of two waves y1 = 0.05 Sin(3πt – 2x) and y2 = 0.05 Sin(3πt + 2x) where x and y are in meters and t is in seconds.
The distance ( in meters ) between two consecutive nodes is …….
  • π/2
  • π
  • 0.5
  • 1.0
0:0:1


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