Question

What is the doppler effect

Answer 1

The Doppler effect is the change in frequency or wavelength of a wave for an observer who is moving relative to the wave source. It is named after the Austrian physicist Christian Doppler, who described the phenomenon in 1842

Answer 2

Doppler effect refers to apparent change in frequency/wavelength of the source due to the relative motion between the source and the observer. The frequency increases apparently if the source and observer approach each other and it decreases apparently if the source and the observer move away from each other.

When, apparent frequency increases, it is known as blue-shift and if it decreases, it is known as red-shift.