Doppler effect

The Doppler effect is a phenomenon observed when there is a change in frequency or wavelength of a wave in relation to an observer moving relative to the source of the wave. Commonly experienced with sound waves, it causes the pitch to sound higher as the source approaches and lower as it moves away. This effect also applies to electromagnetic waves, such as light, and has important applications in fields like astronomy, radar, and medical imaging. Use this tag for posts discussing the Doppler effect, its principles, examples, and related scientific concepts.