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MHT CET 2025 (25 Apr, Shift 2) · Doppler Effect

Doppler Effect question from MHT CET 2025 (25 Apr, Shift 2)

Q9MHT CET 2025 · 25 APR · SHIFT 2Easy

Doppler Effect

At what speed should a source of sound move so that the observer finds the apparent frequency equal to half the original frequency?

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Answer: (d)

  1. A lower frequency means the source moves away: n′=nVV+vsn' = n\frac{V}{V + v_s}.
  2. n2=nVV+vs⇒V+vs=2V\frac{n}{2} = n\frac{V}{V + v_s} \Rightarrow V + v_s = 2V
  3. vs=Vv_s = V, moving away from the observer. So the answer is (d) V.
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