Consider the Doppler effect in two cases. In the first case, an observer moves towards a stationary source of sound with a speed of 50 m/s. In the second case, the observer is at rest and the source moves towards the observer with the same speed of 50 m/s. Then the frequency heard by the observer will be [velocity of sound in air = 330 m/s.] (a) same in both the cases. (b) more in the second case than in the first case. (c) less in the second case than in the first case. (d) less than the actual frequency in both the cases.

Answer: (b). Observer moving: f₁ = f (330 + 50)/(330) ≈ 1.15f. Source moving: f₂ = f (330)/(330 - 50) ≈ 1.18f. So the answer is (b) more in the second case.

Consider the Doppler effect in two cases. In the first case, an… | MHT CET 2023 (10 May, Shift 1)

Q36MHT CET 2023 · 10 MAY · SHIFT 1Medium

Doppler Effect

Consider the Doppler effect in two cases. In the first case, an observer moves towards a stationary source of sound with a speed of $50\text{ m/s}$ . In the second case, the observer is at rest and the source moves towards the observer with the same speed of $50\text{ m/s}$ . Then the frequency heard by the observer will be

[velocity of sound in air $= 330\text{ m/s}$ .]

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Answer: (b)

Observer moving: $f_1 = f\,\dfrac{330 + 50}{330} \approx 1.15f$ .
Source moving: $f_2 = f\,\dfrac{330}{330 - 50} \approx 1.18f$ .
So the answer is (b) more in the second case.

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Doppler Effect question from MHT CET 2023 (10 May, Shift 1)

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