alleryStart learning →An ambulance siren passes you at speed. What happens to the pitch you hear?
AIt stays exactly the same throughout
BIt rises from low pitch to high pitch
CIt shifts from high pitch to low pitch
DIt disappears entirely as it passes
Answer & Solution
Correct answer: C. It shifts from high pitch to low pitch
1. This is the standard everyday example of the Doppler effect.
2. As the ambulance passes, the siren shifts from high pitch to low pitch.
3. Approaching, the compressions bunch up, so the wavelength shortens and pitch rises.
4. Receding, they spread out, so the wavelength lengthens and pitch falls.
_Source: OpenStax Physics (high school, CC BY 4.0), Ch 14 "Sound", section 14.3 Doppler Effect and Sonic Booms_
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