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14. waves and sound — Physics STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 SciencePhysics14. waves and sound1 Mark
MCQ
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 $n + {n_1}$. Then (if the sound velocity in air is $300\, m/s$)
  • A
    ${n_1} = 10\,n$
  • ✓
    ${n_1} = 0$
  • C
    ${n_1} = 0.1\,n$
  • D
    ${n_1} = - 0.1\,n$
✓

Answer

Correct option: B.
${n_1} = 0$
b
(b) In this case Doppler’s effect is not applicable.

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