What is the doppler effect? Summary if possible please.

Answer 1

The Doppler effect is a phenomenon in which the frequency of a wave is perceived to be different when the source and observer are in motion relative to each other. This effect is most commonly observed with sound waves, but can also be seen with light waves, radio waves, and other forms of electromagnetic radiation. The Doppler effect is named after Austrian physicist Christian Doppler, who first described it in 1842.