A small source of sound moves on a circle as shown-in figure (16-Q1) a

1.	A small source of sound moves on a circle as shown-in figure (16-Q1) and an observer is sitting at o. Let v1, v2, v3 be the frequencies heard when the sours.e-is-at A, B and C respectively.(a) v1>v2>v3(b) v1 = v2 > v3(c) v2 > v3 > v1(d) v1 > v2 > v2.
Answer» (c) v₂ > v₂ > v₁ EXPLANATION: When the source is at C the source speed is perpendicular to the line joining the observer and the source. Thus at this instant, the separation between the two is not changing and the frequency heard ν₃ is same as the source. When the source is at A the separation between them is increasing, so due to the Doppler effect ν₁ < ν₃. But when the source is at B, the separation is decreasing and due to the Doppler effect ν₃ < ν₂. So ν₂ > ν₃ > ν₁. Hence the option (c).

A small source of sound moves on a circle as shown-in figure (16-Q1) and an observer is sitting at o. Let v1, v2, v3 be the frequencies heard when the sours.e-is-at A, B and C respectively.(a) v1>v2>v3(b) v1 = v2 > v3(c) v2 > v3 > v1(d) v1 > v2 > v2.

Answer»

(c) v₂ > v₂ > v₁

EXPLANATION:

When the source is at C the source speed is perpendicular to the line joining the observer and the source. Thus at this instant, the separation between the two is not changing and the frequency heard ν₃ is same as the source. When the source is at A the separation between them is increasing, so due to the Doppler effect ν₁ < ν₃. But when the source is at B, the separation is decreasing and due to the Doppler effect ν₃ < ν₂. So ν₂ > ν₃ > ν₁. Hence the option (c).

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