Q10 of 36 Page 105

A train whistling at constant frequency is moving towards a station at a constant speed V. The train goes past a stationary observer on the station. The frequency n′ of the sound as heard by the observer is plotted as a function of time t (Fig 15.1). Identify the expected curve.

When the train is coming towards the observer

c.PNG


Apparent frequency


Now;


The train is going away from the observer


Apparent frequency


So,


The curve formed is C.

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