Doppler's effect in light is symmetrical but the same effect in sound is asymmetrical. Explain.

Explanation

A material medium is required for sound waves to propagate. So, when the source moves towards the observer, the observed frequency is different from the case when the observer moves towards the source with the same relative velocity. So, we can say that Doppler effect in sound is asymmetric. On the other hand, material medium is not required for the propagation of light waves. So, the observed frequency is same irrespective of whether the observer moves towards the source or source moves towards the observer. Therefore, Doppler effect in light is symmetric and in sond is asymmetric.