This page explains the Doppler effect, introduced by Christian Doppler in 1842, describing how the frequency of waves changes due to the relative motion between the observer and source. It is notably ...This page explains the Doppler effect, introduced by Christian Doppler in 1842, describing how the frequency of waves changes due to the relative motion between the observer and source. It is notably observed in sound, as with sirens, where frequency increases when approaching and decreases when moving away.
