An observer moves towards a stationary source of from Class Physics Waves

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NEET Physics : Waves

Multiple Choice Questions

21.

A closed argon pipe and an open argon pipe are tuned to the same fundamental frequency. What is the ratio of their lengths?

  • 1:2

  • 2:1

  • 2:3

  • 4:3



22.

 A particle is executing two different simple harmonic motions, mutually perpendicular, of different amplitudes and having phase difference of π2 The path of the particle will be

  • circular

  • straight line

  • parabolic

  • elliptical



23.

The time of reverberation of a room A is one second. What will be the time (in seconds) of reverberation of a room, having all the dimensions double of those of room A?

  • 2

  • 4

  • 12

  • 1



24.

A particle is executing the motion x = αcos(ωt-θ).The velocity of the particle is

  • αω cosθ

  • αω

  • αω sinθ

  • None of the above



25.

A person is observing two trains one coming towards him and other leaving with the same
velocity 4 m/s. If their whistling frequencies are 240 Hz each, then the number of beats per second heard  by the person will be : ( if velocity of sound 320 m/s)

  • 3

  • 6

  • 9

  • zero



26.

There are 26 tuning forks arranged in the decreasing order of their frequencies. Each tuning fork gives 3 beats with the next. The first one is octave of the last. What is the frequency of 18th tuning fork?

  • 100 Hz

  • 99 Hz

  • 96 Hz

  • 103 Hz



27.

A point source emits sound equally in all directions in a non-absorbing medium. Two points P and Q are at distance of 2m and 3m respectively from the source. The ratio of the intensities of the waves at P and Q is

  • 9:4

  • 2:3

  • 3:2

  • 4:9



28.

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 ?

  • Zero

  • 0.5 %

  • 5 %

  • 20 %



29.

Two vibrating tuning forks produce progressive waves given by y1 = 4 sin 500 πt and y2 = 2 sin 506 Πt. Number of beats produced per minute is

  • 360

  • 180

  • 3

  • 60



30.

Which one of the following statements is true?

  • Both light and sound waves in air are transverse

  • The sound waves in air are longitudinal while the light waves are transverse

  • Both light and sound waves in air are longitudinal

  • Both light and sound waves can travel in vacuum



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