Q157 / 160 · AP EAMCET 2020 (23 Sep Shift 1) · Physics

A source is stationary and the observer is in motion along a line joining the source and the observer. If the frequency heard by the observer is 1% higher than the true frequency, the ratio of velocity of the observer and that of sound in air is:

  • Correct answer
    A
    1:100
  • B
    2:100
  • C
    3:100
  • D
    1:10

Solution

As source is stationary and the observer is moving with velocity vo

Let velocity of sound v

Observed frequency f in Doppler effect is given by 

f=v+vovfo       Here f=1.01fo(Given)

⇒1.01fo=v+vovfo⇒101100=v+vov⇒vov=1100

Hence, the correct answer is option: 'A'.

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