A) \[2486\,\,Hz\]
B) \[2070\,\,Hz\]
C) \[2134\,\,Hz\]
D) \[1872\,\,Hz\]
Correct Answer: B
Solution :
Key Idea: Movement of the source and observer alters the wavelength and the perceived frequency of sound. As both source and observer are moving away, so observed frequency decreases. \[\therefore \] \[f'=\left( \frac{v-{{v}_{o}}}{v+{{v}_{s}}} \right)f\] where \[v\] is the velocity of sound\[=340\,\,m/s\]. Here,\[{{v}_{o}}=20\,\,m/s,\,\,{{v}_{s}}=20\,\,m/s,\,\,f'=1840\,\,Hz\] \[\therefore \] \[1840=\left( \frac{340-20}{340+20} \right)f\] or \[f=\frac{1840\times 360}{320}=2070\,\,Hz\]You need to login to perform this action.
You will be redirected in
3 sec