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AP EAMCET201920 Apr 2019Morning ShiftPhysicsWaves and SoundActual

An observer moves towards a stationary source of sound with a speed ( 1 5 ^ th ) of the speed of sound. The wavelength and frequency of the waves emitted by the source are ( ) and (f ) respectively. The apparent frequency and wavelength heard by the observer are respectively,

Options

  1. A(1.2 f, )
  2. B(f, 1.2 )
  3. C(0.8 f, 0.8 )
  4. D(1.2 f, 1.2 )

Correct answer

A. (1.2 f, )

Step-by-step solution

When an observer moves towards on a stationary source of sound, then apparent frequency heard by the observer increases. The apparent frequency heard in this situation. (f^ = ( v+v₀ v-v_s ) f, ) (As source is stationary) Hence, (v_s=0 ) ( aligned & f^ = ( v+v₀ v ) f & Given, v₀= v 5 & f^ = ( v+ v 5 v ) f= 6 5 f=1.2 f aligned ) Motion of the observer does not affect the wavelength reaching the observer, hence wavelength remains ( ). Hence, the apparent frequency and wavelength heard by the observes are respectively,

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