Doppler Effect

Definition

The Doppler Effect is the change in frequency or wavelength of a wave as observed by an observer moving relative to the source of the wave. It occurs when there is relative motion between the source and the observer.

Related terms

Frequency:

The number of complete cycles of a wave that occur in one second.

Wavelength:

The distance between two consecutive points on a wave.

Redshift/Blueshift: Redshift refers to an increase in wavelength (and decrease in frequency) due to an object moving away, while blueshift refers to a decrease in wavelength (and increase in frequency) due to an object moving closer.