A train whistling at constant frequency is moving towards a stati… - Vidyadip

MCQ

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.) . Identify the expected curve

A
B
✓
D

✓

Answer

Correct option: C.

c
Approaching source $\mathrm{n}^{\prime}=\mathrm{n}\left[\frac{\mathrm{V}}{\mathrm{V}-\mathrm{V}_{\mathrm{s}}}\right]$ constant

Receading source $\mathrm{n}^{\prime}=\left[\frac{\mathrm{V}}{\mathrm{V}+\mathrm{V}_{\mathrm{s}}}\right]$ constant.

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