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Waves — Physics STD 11 Science — Question

Rajasthan BoardEnglish MediumSTD 11 SciencePhysicsWaves3 Marks
Question
A source and an observer are approaching one another with velocity 4m/s. If the true frequency is 1200Hz, deduce the observed frequency under the following conditions:
  1. All velocity is in the source alone.
  2. All velocity is in the observer alone.
Take the velocity of sound waves in air to be 340ms-1.
✓

Answer

  1. $\text{v}'=\text{v}\Big(\frac{\nu}{\nu-\nu_\text{s}}\Big)=1200\Big(\frac{340}{336}\Big)\text{ft}$

$=1214.28\text{Hz}$

  1. $\text{v}'=\text{v}\Big(\frac{\nu+\nu_0}{\nu_0}\Big)=1200\Big(\frac{344}{340}\Big)$

$=1214.11\text{Hz}$

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