Mondo Knows Facts
Moving wave sources shift frequency relative to observers
The Doppler effect compresses approaching sound waves and stretches departing ones
As a sound or light source moves toward an observer, each successive wave crest is emitted from a position closer to the listener, shortening the apparent wavelength and raising the frequency. As the source recedes, wavelengths stretch out and frequency drops. Astronomers use this effect to measure how fast distant galaxies move away from Earth.
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Tags: physics, doppler effect, waves
Moving wave sources shift frequency relative to observers: the short answers
- Where does this come from, and can I check it?
- The Doppler effect compresses approaching sound waves and stretches departing ones. The figure is taken from NOAA, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.
- Is this really a science fact?
- Yes. It sits on the Science shelf, one of 1,090 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.
- What else can I read about it?
- The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.