With what velocity an observer should move relative to a stationa… - Vidyadip

MCQ

With what velocity an observer should move relative to a stationary source so that he hears a sound of double the frequency of source

✓
Velocity of sound towards the source
B
Velocity of sound away from the source
C
Half the velocity of sound towards the source
D
Double the velocity of sound towards the source

✓

Answer

Correct option: A.

Velocity of sound towards the source

a
(a)By using $n' = n\,\left( {\frac{v}{{v - {v_S}}}} \right)$
$2n = n\,\left( {\frac{{v - {v_O}}}{{v - 0}}} \right)$ ==> ${v_O} = - v = - $(Speed of sound)
Negative sign indicates that observer is moving opposite to the direction of velocity of sound, as shown

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