A boy is walking away from a wall towards an observer at a speed of 1 metre/sec and blows a whistle whose frequency is 680 Hz. The number of beats heard by the observer per second is (Velocity of sound in air = 340 metres/sec [MP PMT 1995]

A boy is walking away from a wall towards an observer at a speed of 1

1.	A boy is walking away from a wall towards an observer at a speed of 1 metre/sec and blows a whistle whose frequency is 680 Hz. The number of beats heard by the observer per second is (Velocity of sound in air = 340 metres/sec [MP PMT 1995]
A.	Zero
B.	2
C.	\[3.138\times {{10}^{-7}}m\]
D.	4
Answer» E.

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A boy is walking away from a wall towards an observer at a speed of 1 metre/sec and blows a whistle whose frequency is 680 Hz. The number of beats heard by the observer per second is (Velocity of sound in air = 340 metres/sec [MP PMT 1995]

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