A) 3
B) 1 / 2
C) 2
D) 1
Correct Answer: C
Solution :
When listener moves \[f'=f\,\left( \frac{v+{{v}_{\ell }}}{v} \right)\] when moves away \[\frac{f'}{f''}\,\,=\,\,f\left( \frac{v-{{v}_{\ell }}}{v} \right)\] \[\frac{f'}{f''}\,\,=\,\,3\] \[\Rightarrow \,\,\frac{v+{{v}_{\ell }}}{v-{{v}_{\ell }}}\,\,=\,\,3\] \[\Rightarrow \,\,\,v+{{v}_{\ell }}=3v-3{{v}_{\ell }}\] \[\Rightarrow \,\,\,\,4{{v}_{\ell }}=\,\,2v\] \[\Rightarrow \,\,\,v=2{{v}_{\ell }}\] \[\frac{v}{{{v}_{\ell }}}=2\]You need to login to perform this action.
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