JEE Questions for Physics Waves Quiz 16 - MCQExams.com

Two plane harmonic sound waves are expressed by the equations.
y1 (x, t = A cos (0.5 πx – 100 πt)
yx (x, t = A cos (0.4 πx – 92 πt)
(All parameter are in MKS)
How many times does an observer hear maximum intensity in one second?
  • 4
  • 10
  • 6
  • 8
Two plane harmonic sound waves are expressed by the equations.
y1 (x, t = A cos (0.5 πx – 100 πt)
yx (x, t = A cos (0.4 πx – 92 πt)
(All parameter are in MKS)
What is the speed of the sound?
  • 200 m/s
  • 180 m/s
  • 192 m/s
  • 96 m/s
Two plane harmonic sound waves are expressed by the equations.
y1 (x, t = A cos (0.5 πx – 100 πt)
yx (x, t = A cos (0.4 πx – 92 πt)
(All parameter are in MKS)
At x = 0 how many times the amplitude of y1 + y2 is zero in one second?
  • 192
  • 48
  • 100
  • 96
Two trains A and B are moving with speeds 20 m/s and 30 m/s respectively in the same direction on the same straight track, with B ahead of A. The engines are at the front end. The engine of train A blows a long whistle.
Assume that the sound of the whistle is composed of components varying in frequency from f1. = 800Hz to f2 = 1120 Hz, as shown in the figure. The spread in the frequency (highest frequency-lowest frequency) is thus 320 Hz. The speed of sound in still are is 340 m/s.
The speed of sound of the whistle is
Physics-Waves-96960.png
  • 340 m/s for passengers in A and 310 m/s for passengers in B
  • 360 m/s for passengers in A and 360 m/s for passengers in B
  • 310 m/s for passengers in A and 360 m/s for passengers in B
  • 340 m/s for passengers in both the trains
Two trains A and B are moving with speeds 20 m/s and 30 m/s respectively in the same direction on the same straight track, with B ahead of A. The engines are at the front end. The engine of train A blows a long whistle.
Assume that the sound of the whistle is composed of components varying in frequency from f1. = 800Hz to f2 = 1120 Hz, as shown in the figure. The spread in the frequency (highest frequency-lowest frequency) is thus 320 Hz. The speed of sound in still are is 340 m/s.
The distribution of the sound intensity of the whistle as observed by the passengers in train A is best represented by
Physics-Waves-96962.png

  • Physics-Waves-96963.png
  • 2)
    Physics-Waves-96964.png

  • Physics-Waves-96965.png

  • Physics-Waves-96966.png
Two trains A and B are moving with speeds 20 m/s and 30 m/s respectively in the same direction on the same straight track, with B ahead of A. The engines are at the front end. The engine of train A blows a long whistle.
Assume that the sound of the whistle is composed of components varying in frequency from f1. = 800Hz to f2 = 1120 Hz, as shown in the figure. The spread in the frequency (highest frequency-lowest frequency) is thus 320 Hz. The speed of sound in still are is 340 m/s.
The spread of frequency as observed by the passengers in train B is
Physics-Waves-96967.png
  • 310 Hz
  • 330 Hz
  • 350 Hz
  • 290 Hz
Column I shows four systems, each of the same length L, for producing standing waves. The lowest possible natural frequency of a system is called its fundamental frequency, whose wavelength is denoted as λf Match each system with statements given in Column II describing the nature and wavelength of the standing waves.
Physics-Waves-96969.png

  • Physics-Waves-96970.png
  • 2)
    Physics-Waves-96971.png

  • Physics-Waves-96972.png

  • Physics-Waves-96973.png
Assertion Two persons on the surface of moon cannot talk to each other.
Reason There is no atmosphere on moon.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion Transverse waves are not produced in liquids and gases.
Reason Light waves are transverse waves.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion Sound waves cannot propagate through vacuum but light waves can.
Reason Sound waves cannot be polarized but light waves can be polarized.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion The change in air pressure effects the speed of sound.
Reason The speed of sound in gases is proportional to the square of pressure.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion The reverberation time dependent on the shape of enclosure, position of source and observer.
Reason The unit of absorption coefficient in mks system is metric sabine.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion When a beetle moves along the sand with in a few tens of centimetres of a sand scorpion the scorpion immediately turn towards the beetle and dashes to it.
Reason When a beetle disturbs the sand, it sends pulses along the sands surface one set of pulses is longitudinal while other set is transverse.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion Transverse waves travel through air in an organ pipe.
Reason Air possesses only volume elasticity.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion Sound would travel faster on a hot summer day than on a cold winter day.
Reason Velocity of sound is directly proportional to the square of its absolute temperature.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion The basic of Laplace correction was that, exchange of heat between the region of compression and rarefaction in air is not possible.
Reason Air is a bad conductor of heat and velocity of sound in air is large.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion Particle velocity and wave velocity both are independent of time.
Reason For the propagation of wave motion, the medium must have the properties of elasticity and inertia.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion The flash of lightening is seen before the sound of thunder is heard.
Reason Speed of sound is greater than speed of light.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion A tuning fork is made of an alloy of steel, nickel and chromium.
Reason The alloy of steel, nickel and chromium is called elinvar.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion The change in air pressure effect the speed of sound.
Reason The speed of sound in a gas is proportional to square root of pressure.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion Solids can support both longitudinal and transverse waves but only longitudinal waves can propagate in gases.
Reason For the propagation of transverse waves, medium must also necessarily have the property of rigidity.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion Under given conditions of pressure and temperature, sound travels faster in a monoatomic gas than in diatomic gas.
Reason Opposition for wave to travel is more in diatomic gas than monoatomic gas.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion The speed of sound in solids is maximum though their density is large.
Reason The coefficient of elasticity of solid is large.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion On a rainy day sound travels slower than on a dry day.
Reason When moisture is present in air the density of air increases.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.

Physics-Waves-96981.png
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion Sound produced by an open organ pipe is richer than the sound produced by a closed organ pipe.
Reason Outside air can enter the pipe from both ends, in case of open organ pipe.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion It is not possible to have interference between the waves produced by two violins.
Reason For interference of two waves the phase difference between the waves must remain constant.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion Like sound, light can not propagate in vacuum.
Reason Sound is a square wave. It propagates in a medium by a virtue of damping oscillation.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false
  • If Assertion is false but Reason is true.
Assertion In the case of a stationary wave, a person hear a loud sound at the nodes as compared to the antinodes.
Reason In a stationary wave all the particles of the medium vibrate in phase
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion Velocity of particles, while crossing mean position (in stationary waves) varies from maximum at antinodes to zero at nodes.
Reason Amplitude of vibration at antinodes is maximum and at nodes, the amplitude is zero, And all particles between two successive nodes cross the mean position together.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion Where two vibrating tuning forks having frequencies 256 Hz and 512 Hz are held near each other, beats cannot be heard.
Reason The principle of superposition is valid only if the frequencies of the oscillators are nearly equal.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion The fundamental frequency of an open organ pipe increases as the temperature is increased.
Reason As the temperature increases, the velocity of sound increases more rapidly than length of the pipe.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion Sound travels faster in solids than gases.
Reason Solid posses greater density than gases.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
An engine is moving on a circular track with a constant speed. It is blowing a whistle of frequency 500 Hz. The frequency received by an observer standing stationary at the centre of the track is
Physics-Waves-96986.png
  • 500 Hz
  • More than 500 Hz
  • Less than 500 Hz
  • More or less than 500 Hz depending on the actual speed of the engine
Out of the following, incorrect statement is
  • In Melde's experiment "P2T" remain constant. (P = Loop, T =Tension)
  • In Kundt's experiment distance between two heaps of powder is λ/2.
  • Quinckeey's tube experiment related with beats.
  • Echo phenomena related with reflection of sound.
To raise the pitch of a stringed musical instrument the player can
  • Loosen the string
  • Tighten the string
  • Shorten the string
  • Both (b) and (c)
A wave travelling along positive x-axis is given by y = A sin (ωt – kx). If it is reflected from rigid boundary such that 80% amplitude is reflected, then equation of reflected wave is
  • y = A sin (ωt + kx)
  • y = – 0.8A sin (ωt + kx)
  • y = 0.8A sin (ωt + kx)
  • y = A sin (ωt + 0.8kx)
An engine approaches a hill with a constant speed. When it is at a distance of 0.9 km it blows a whistle, whose echo is heard by the driver after 5 sec. If speed of sound in air is 330 m/s, the speed of engine is
Physics-Waves-96989.png
  • 10 m/s
  • 20 m/s
  • 30 m/s
  • 40 m/s
A sound wave of wavelength 32 cm enters the tube at S as shown in the figure. Then the smallest radius r so that a minimum of sound is heard at detector D is
Physics-Waves-96991.png
  • 7 cm
  • 14 cm
  • 21 cm
  • 28 cm
A stretched wire of length 110 cm is divided into three segments whose frequencies are in ratio 1 : 2 : 3. Their lengths must be
  • 20 cm ; 30 cm; 60 cm
  • 60 cm; 30 cm; 20 cm
  • 60 cm ; 20 cm ; 30 cm
  • 30 cm ; 60 cm; 20 cm
Unlike a laboratory sonometer, a stringed instrument is seldom plucked in the middle. Supposing a sitar string is plucked at about 1/4 th of its length from the end. The most prominent harmonic would be
  • Eighth
  • Fourth
  • Third
  • Second
If n1, n2, n3 are the frequencies of segments of a stretched string, the frequency n of the string is given by

  • Physics-Waves-96994.png
  • 2)
    Physics-Waves-96995.png

  • Physics-Waves-96996.png
  • None of the above

Physics-Waves-96997.png
  • 6 cm
  • 4 cm
  • 3 cm
  • 1.5 cm
An Indian submarine and an enemy submarine move towards each other during maneuvers in motionless water in the Indian ocean. The Indian submarine moves at 50 km/h, and the enemy submarine at 70 km/h. The Indian sub sends out a sonar signal (sound wave in water) at 1000 Hz. Sonar waves travel at 5500 km/h. What is the frequency detected by the Indian submarine
Physics-Waves-96999.png
  • 1.04 kHz
  • 2 kHz
  • 2.5 kHz
  • 4.7 kHz
Two trains, one coming towards and another going away from an observer both at 4 m/s produce whistle simultaneously of frequency 300 Hz. Find the number of beats produced
  • 5
  • 6
  • 7
  • 12
A source of sound emits 400 πW power which is uniformly distributed over a sphere of 10 m radius. What is the loudness of sound on the surface of a sphere?
  • 200 dB
  • 200 π dB
  • 120 dB
  • 120 π dB
In the 3rd overtone of an open organ pipe, there are (N-stands for nodes and A -for antinodes)
  • 2N, 3A
  • 3N, 4A
  • 4N, 5A
  • 5N, 4A
A sine wave has an amplitude A and wavelength λ. Let V be the wave velocity and v be the maximum velocity of a particle in the medium. Then

  • Physics-Waves-97003.png
  • 2)
    Physics-Waves-97004.png

  • Physics-Waves-97005.png
  • V cannot be equal to v

Physics-Waves-97007.png

  • Physics-Waves-97008.png
  • 2)
    Physics-Waves-97009.png

  • Physics-Waves-97010.png
  • 2
A tuning fork A produces 4 beats/sec with another tuning fork B of frequency 320 Hz. On filing the fork A, 4 beats/sec are again heard. The frequency of fork A, after filing is
  • 324 Hz
  • 320 Hz
  • 316 Hz
  • 314 Hz
0:0:1


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