Question:
A train moves towards a stationary observer with speed 34 m/s. The train sounds a whistle and its frequency registered by the observer is \(f_1\). If the speed of the train is reduced to 17 m/s, the frequency registered is \(f_2\). If speed of sound is 340 m/s, then the ratio \(f_1/f_2\) is -
A train moves towards a stationary observer with speed 34 m/s. The train sounds a whistle and its frequency registered by the observer is \(f_1\). If the speed of the train is reduced to 17 m/s, the frequency registered is \(f_2\). If speed of sound is 340 m/s, then the ratio \(f_1/f_2\) is -
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Use \(f = f_0\frac{v}{v-v_s}\) for a source approaching a stationary observer.
Updated On: Nov 5, 2026
- 19/18
- 20/19
- 21/20
- 18/17
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The Correct Option is A
Solution and Explanation
\(f_1 = f_0\frac{340}{340-34} = f_0\frac{340}{306}\) and \(f_2 = f_0\frac{340}{340-17} = f_0\frac{340}{323}\).
\(\frac{f_1}{f_2} = \frac{323}{306} = \frac{19}{18}\) (dividing numerator and denominator by 17).
Answer: (1) 19/18
\(\frac{f_1}{f_2} = \frac{323}{306} = \frac{19}{18}\) (dividing numerator and denominator by 17).
Answer: (1) 19/18
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