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A sound source S is moving along a straight track with speed v , and is emitting sound of frequency v 0 .An observer is standing at a finite distance, at the point O , from the track. The time variation of frequency heard by observer is best represented by : (to represents the instant when the distance between the source and observer is minimum)

Correct answer

1

Step-by-step solution

Observed frequency will be v = V sound  + V cos θ V sound  v 0 Using this formula we can say that observed frequency will decrease continuously and it becomes equal to original frequency when θ =   90 ° . So correct graph is

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