Home > Terms > English, UK (UE) > Doppler shift principle

When a source generating waves moves relative to an observer, or when an observer moves relative to a source, there is an apparent shift in frequency. If the distance between the observer and the source is increasing, the frequency apparently decreases, while the frequency apparently increases if the distance between the observer and the source is decreasing. This relationship is called the Doppler effect (or Doppler shift) after Austrian physicist Christian Johann Doppler (1803–1853).