Question
Sat November 19, 2011 By:

please explain what is Doppler effect

Expert Reply
Sat November 19, 2011
When there is a relative motion between a source of sound and the listener, the apparent frequency of sound heard and the actual frequency of sound emitted by the source are different.
When the distance between the source and the listener decreases, the apparent frequency increases; and when the distance between the source and the listener increases, the apparent frequency decreases.
For e.g., if we stand along a road and an ambulance approaches sounding its siren, we will hear sound of increasing frequency as the ambulance approaches, and decreasing frequency as the ambulance recedes.
Ask the Expert