Explanation:
Doppler effect: It is the phenomenon in which there is relative motion between the source and the observer or the source and the listener. There is an apparent change in the frequency.
When the observer and the source are moving towards each other then the frequency increases.
When the observer and the source are moving away from each other then the frequency decreases.
The expression of the speed of the wave in terms of the frequency is as follows;
Here, v is the speed of the wave, f is the frequency of the wave and is the wavelength of the wave.
From the above relation, it can be concluded that speed of the sound is directly proportional to the frequency of the wave.
The magnitude of the Doppler shift increases when the velocity of the sound source is increased.