With what velocity an observer should move relative to a stationary source so that a sound of double the…
With what velocity an observer should move relative to a stationary source so that
a sound of double the frequency of source is heard by an observer?
Half the velocity of sound towards the source.
Same as velocity of sound away from the source.
Twice the velocity of sound towards the source.
Same as velocity of sound towards the source.
Solution
Correct option is A)
By using $n^{\prime}=n\left(\frac{v}{v-v_{s}}\right)$
$2 \mathrm{n}=\mathrm{n}\left(\frac{\mathrm{v}-\mathrm{v}_{0}}{\mathrm{v}-0}\right)$
$\Rightarrow \mathrm{v}_{0}=-\mathrm{v}=-($ Speed of sound $)$
Negative sign indicates that observer is moving opposite to the direction of velocity of sound, as shown