Waves & Sound · JEE Main previous year questions

2022 5 questions

1. Q592022 · 30 Jun 2022 · Shift 1· Numerical answer

   An employee of a factory moving away from his workplace by a car listens to the siren of the factory. He drives the car at the speed of $72{\text{ kmh}}^{-1}$ in the direction of wind which is blowing at $72{\text{ kmh}}^{-1}$ speed. Frequency of siren is $720\text{ Hz}$. The employee hears an apparent frequency of ___________ Hz. (Assume speed of sound to be $340{\text{ ms}}^{-1}$)

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   Answer: 680

2. Q572022 · 28 Jun 2022 · Shift 2· Numerical answer

   A tuning fork of frequency $340\mathrm{Hz}$ resonates in the fundamental mode with an air column of length $125\mathrm{cm}$ in a cylindrical tube closed at one end. When water is slowly poured in it, the minimum height of water required for observing resonance once again is ____ $\mathrm{cm}$. (Velocity of sound in air is $340\mathrm{m}{\mathrm{s}}^{-1}$)

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   Answer: 50

3. Q502022 · 27 Jun 2022 · Shift 1

   An observer moves towards a stationary source of sound with a velocity equal to one-fifth of the velocity of sound. The percentage change in the frequency will be :

   1. A.20%
   2. B.10%
   3. C.5%
   4. D.0%
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   Answer: A

4. Q552022 · 26 Jun 2022 · Shift 2· Numerical answer

   A set of 20 tuning forks is arranged in a series of increasing frequencies. If each fork gives 4 beats with respect to the preceding fork and the frequency of the last fork is twice the frequency of the first, then the frequency of last fork is _________ Hz.

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   Answer: 152

5. Q542022 · 25 Jun 2022 · Shift 1· Numerical answer

   The first overtone frequency of an open organ pipe is equal to the fundamental frequency of a closed organ pipe. If the length of the closed organ pipe is 20 cm, the length of the open organ pipe is _____________ cm.

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   Answer: 80