Doppler effect


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Related to Doppler effect: Doppler radar, CT scan, MRI

Dop·pler effect

 (dŏp′lər)
n.
A change in the observed frequency of a wave, as of sound or light, occurring when the source and observer are in motion relative to each other, with the frequency increasing when the source and observer approach each other and decreasing when they move apart. The motion of the source causes a real shift in frequency of the wave, while the motion of the observer produces only an apparent shift in frequency. Also called Doppler shift.

[After Christian Andreas Doppler (1803-1853), Austrian physicist and mathematician who explained the phenomenon.]

Doppler effect

(ˈdɒplə)
n
(General Physics) a phenomenon, observed for sound waves and electromagnetic radiation, characterized by a change in the apparent frequency of a wave as a result of relative motion between the observer and the source. Also called: Doppler shift
[C19: named after C. J. Doppler (1803–53), Austrian physicist]

Dop′pler effect`

(ˈdɒp lər)
n.
a phenomenon characterized by a change (Dop′pler shift`) in the frequency of waves, as light or sound waves, observed when the wave source is moving relative to the observer.
[1900–05; after C. J. Doppler (1803–53), Austrian physicist]
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Doppler effect
As the source of sound waves (the ambulance) moves closer to the observer, the frequency of the sound waves and pitch of the sound become higher. As the source moves away from the observer, the frequency and pitch become lower.

Dop·pler effect

(dŏp′lər)
The apparent change in the frequency of waves, as of sound or light, when the source of the waves is moving toward or away from an observer.
Did You Know? When a car rushes past you on the road with the driver holding down the horn, you hear the horn change tone: it's higher pitched than normal as the car approaches and lower pitched as it departs. That's because of the Doppler effect. Sound waves spread outward in all directions from the horn. The forward motion of the car compresses the sound waves traveling ahead of the car, making the wavelengths shorter. Sound having shorter wavelengths has higher frequency and therefore higher pitch—what you hear if the car is moving towards you. Behind the car, however, the sound waves are drawn apart. Longer wavelengths mean lower frequency and lower pitch, which is what you hear once the car rushes past. The Doppler effect works on light waves, too; in fact, this was how scientists determined that the universe is expanding. The light from galaxies and other distant celestial objects is shifted toward the red end of the spectrum (a phenomenon called red shift). Red light has the longest wavelengths of visible light. The pioneering astronomer Edwin Hubble reasoned that the red shift was due to the Doppler effect: the galaxies are speeding away from us, drawing out the wavelengths of the light emitted behind them, and the universe as a whole is expanding.

doppler effect

The phenomenon evidenced by the change in the observed frequency of a sound or radio wave caused by a time rate of change in the effective length of the path of travel between the source and the point of observation.

döppler effect

Apparent change in the frequency of light waves or sound waves due to the relative motion of the observer and the source of the waves.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.Doppler effect - change in the apparent frequency of a wave as observer and source move toward or away from each other
propagation - the movement of a wave through a medium
Translations
Doppler-Effekt
effet Doppler
dopplereffekt

Doppler effect

[ˈdɒplərɪˌfekt] N (Astron) → efecto m Doppler

Doppler effect

Doppler effect

[ˈdɒplərɪˌfɛkt] n (Phys) → effetto Doppler
References in periodicals archive ?
The combination of the sonic pulse of the Doppler effect and the released power of a sonic boom inspired our celebration of EV Racing.
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Key VRTS attributes include the ability to simulate Doppler effect velocity of up to 250 km/ hr, minimum obstacle range of 4 m, object distance resolution down to 10 cm, support for multiple angles of arrival, and variable radar cross sections.
Redshift refers to the lengthening of the wavelength of light from an object, caused by the Doppler effect as the universe expands.
the movement towards or away from us) by measuring the redshift, which is caused by the Doppler effect.
Following this, receiver units of SmartLife measure the frequency shift of the reflected signal, in accordance with Doppler Effect (which measures the increase/decrease in frequency that occurs when the distance between source and obstacle is altered).
We also evaluate the Doppler effect impact on the proposed dynamic coordination scheme.
The millimeter-wave radar speed sensing module underpins advanced rail traffic operational control by using the electromagnetic wave Doppler effect to measure speed relative to the ground through a non-contact method that provides accurate speed measurements that are unaffected by wheel slip and skidding.
Hands up those who haven't heard of the Doppler Effect.
evidently a Doppler effect, arising from rapid motion of the gas either toward or away from the observer.

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