Question

what is meant by doppler effect. explain in case of sound and light?

Answer 1

An increase in the frequency of sound, light, or other Waves as the source and observe moves towards each other. the effect causes the sudden change in siren, as well as the red shift seen by astronomers.

Answer 2

1). when source (S) and listener (L) both are at rest.

2). when S and L move in fresher way that distance between them remains constant.

3). when source S and L are moving mutually perpendicular direction.