When source of sound and observer both are moving towards each other, the observer will hear (a) low frequency, low wavelength. (b) low frequency, high wavelength. (c) high frequency, low wavelength. (d) high frequency, high wavelength.

Answer: (c). Approaching each other: n' = n(v + vo)/(v - vs) > n, so frequency is higher. The moving source compresses the waves ahead of it: λ' = (v - vs)/(n) < λ. So the answer is (c): high frequency, low wavelength.

When source of sound and observer both are moving towards each other… | MHT CET 2025 (22 Apr, Shift 2)

Q14MHT CET 2025 · 22 APR · SHIFT 2Easy

Doppler Effect

When source of sound and observer both are moving towards each other, the observer will hear

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Answer: (c)

Approaching each other: $n' = n\frac{v + v_o}{v - v_s} > n$ , so frequency is higher.
The moving source compresses the waves ahead of it: $\lambda' = \frac{v - v_s}{n} < \lambda$ .
So the answer is (c): high frequency, low wavelength.

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Doppler Effect question from MHT CET 2025 (22 Apr, Shift 2)

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