Doppler effect

The Doppler effect is a physical phenomenon discovered by Christian Doppler in 1842, which occurs when the source of a sound or an electromagnetic wave moves relative to an observer. It results in a variation of the frequency perceived by the observer, which is higher when the source approaches and lower when the source moves away. This effect is used in many fields, including meteorology, astronomy and medicine. The formula to calculate the Doppler effect is: f' = f(c+v_s)/(c+v_o) where f is the frequency of the source, c is the speed of light, v_s is the speed of the source and v_o is the speed of the observer.