A closed organ pipe of length 20 cm is sounded  from Class Physics Waves

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CBSE

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Physics
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NEET Physics : Waves

Multiple Choice Questions

31.

A closed organ pipe of length 20 cm is sounded with tuning fork in resonance. What is frequency of tuning fork? (v = 332 m/s)

  • 300 Hz

  • 350 Hz

  • 375 Hz

  • 415 Hz



32.

Two vibrating strings of the same material but lengths L and 2L have radii 2r and r respectively. They are stretched under the same tension. Both the strings vibrate in their fundamental modes, the one of length L with frequency v1 and the other with frequency v2 The ratio v1v2 is

  • 2

  • 4

  • 8

  • 1



33.

A closed organ pipe of length 20 cm is sounded with tuning fork in resonance. What is the frequency of tuning fork? (v = 332 m/s)

  • 300 Hz

  • 350 Hz

  • 375 Hz

  • 415 Hz



34.

A tuning fork A produces 4 beats/s with another tuning fork B of frequency 320 Hz. On filing one of the prongs of A, 4 beats/s are again heard when sounded with the same fork B. Then, the frequency of the fork A before filing is

  • 328 Hz

  • 316 Hz

  • 324 Hz

  • 320 Hz



35.

The sound waves after being converted into electrical waves are not transmitted as such because

  • they travel with the speed of sound

  • the frequency is not constant

  • they are heavily absorbed by the atmosphere

  • the height of antenna has to be increased several times



36.

When sound waves travel from air to water which one of the following remains constant?

  • Time period

  • Frequency

  • Velocity

  • Wavelength



37.

y = 3 sin π t2 - x4 represents an equation of a progressive wave, where t is in second and x is in metre. The distance travelled by the wave in 5 s is

  • 8 m

  • 10 m

  • 5 m

  • 32 m



38.

A transverse wave is expressed as, y = yo sin 2πf t  For what value of λ, maximum particle velocity equals to 4 times the wave velocity?

  • yo π2

  • 2 yo π

  • yo π

  • yo π4



39.

An engine moving towards a wall with a velocity 50 m/s  emits a note of 1.2 kHz. Speed of sound in air is 350 m/s. 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



40.

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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