what is the Doppler effect in phisics ?

Question

in french it's called l'Effet Doppler

Answer 1

It is the change in the wavelength and frequency of a wave of a moving object with respect to a stationary object (or vice versa). It is the reason when a passing car honks the horn you hear a pitch change in the horn as it passes you, or how policemen with radar guns determine your speed.

Answer 2

Doppler Effect, in physics, the apparent variation in frequency of any emitted wave, such as a wave of light or sound, as the source of the wave approaches or moves away from an observer. The effect takes its name from the Austrian physicist Christian Johann Doppler, who first stated the physical principle in 1842. Doppler's principle explains why, if a source of sound of a constant pitch is moving towards an observer, the sound seems higher in pitch, whereas if the source is moving away it seems lower. This change in pitch can be heard by an observer listening to the whistle of an express train from a station platform or another train. The lines in the spectrum of a luminous body such as a star are similarly shifted towards the violet if the distance between the star and the Earth is decreasing and towards the red if the distance is increasing. By measuring this shift, the relative motion of the Earth and the star can be calculated .

Answer 3

The Doppler effect, named after Christian Doppler, is the change in frequency and wavelength of a wave that is perceived by an observer moving relative to the source of the waves. For waves, such as sound waves, that propagate in a wave medium, the velocity of the observer and of the source are reckoned relative to the medium in which the waves are transmitted. The total Doppler effect may therefore result from either motion of the source or motion of the observer. Each of these effects is analyzed separately. For waves which do not require a medium, such as light or gravity in special relativity only the relative difference in velocity between the observer and the source needs to be considered.

Answer 4

The doppler effect is when the frequency and wavelength of a sound wave changes due to an object moving in relation to the source of the sound wave. An example is the way an emergency siren changes when it is going towards you and away from you

Answer 5

Its a property of waves, where when the source of the wave moves away from you, the wavelengths are different then when the source is moving towards you. The most common example of this is the sound of cars on a highway. They sound differently when they are coming towards you then when they are moving away from you. The same thing with stars, they are different colors when they are moving away, then when they are moving closer.