Doppler effect
1
6.7
- noun
- /ˈdɑːplər ɪˈfɛkt/
- Specialized
:
efecto Doppler
- The Doppler effect explains why the pitch of a siren seems higher as an ambulance approaches and lower as it moves away.
Galaxies may have very small motions which can give them that so-called Doppler effect.
- Galaxies may have very small motions which can give them that so-called Doppler effect.
Examples
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By doing so, they can determine the velocity of interstellar gas clouds and get a practical application of the Doppler Effect.
Academic text (2005) -
And the shift of these absorption lines, due to the Doppler effect, tells us how fast the star is moving along our line of sight (i.e., the radial velocity).
Academic text (2000) -
Hey, have you ever heard of the Doppler effect?
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This is thanks to the Doppler effect.
Academic text (2004) -
And he was also the first to use the Doppler effect to study the motion of stars.
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And the simple explanation of this was that it's a Doppler effect caused by things moving through space.
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In our technological world, we would call this a Doppler effect.
Academic text (2007) -
Those that hit a moving particle head-on are more energetic than those striking from behind because of the Doppler effect.
Academic text (1996) -
The observed wavelength of the line, which can be shifted away from its original value by the Doppler effect, indicates whether the celestial object is moving toward or away from Earth.
Academic text (1996) -
When a race car speeds past, the change in the sound of the engine is a demonstration of the Doppler effect.
Synonyms
13
6.9
A change in the frequency of waves when the source or observer moves
1
6.5
A change in sound pitch or light colour when the source and observer move
Surface Forms
Morphology
The noun phrase names the effect produced by the Doppler phenomenon: 'Doppler' (the frequency-change phenomenon) combined with 'effect' (a change produced) yields the meaning directly. This is a straightforward compositional pattern that is common cross-linguistically, so a B1 learner who knows both constituents would be able to infer the MWE's meaning.
Etymology
The Doppler effect comes from the simple image of a moving sound or light source: as an ambulance comes toward you the sound waves are squeezed and the siren sounds higher, and as it moves away the waves are stretched and the siren sounds lower. That's why the phrase describes a 'change in pitch' or a 'shift in frequency' when the source and the listener move toward or away from each other.