What does the Doppler effect describe?
AA change in observed frequency
BA change in the wave energy
CA change in the sound power
DA change in the wave speed
Answer & Solution
Correct answer: A. A change in observed frequency
1. The effect appears whenever the source of a wave and the observer move relative to each other.
2. What the observer measures is a different frequency from the one the source is emitting.
3. So the Doppler effect is a change in the observed frequency of the wave.
4. The speed of sound in the medium is not altered by the motion of the source.
_Source: Siyavula Physical Sciences Grade 12 (Everything Science, CC BY 4.0), Chapter 6: Doppler effect_
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