what is doppler effect ? obtain an expression for apparent frequency of sound heard when the source is in motion with respect to an observer at rest .

DOPPLER EFFECT:

there is a change in the apparent frequency which is listen by the observer due to the change in the relative motion between sources and observer. This is known as Doppler Effect. IT was explained by J.C DOPPLER in the year 1842. it was practically demonstrated by ballot in the year 1845 {holland}.

 

Doppler effect: The apparent change in the frequency of sound due to relative motion between source and observer is called doppler effect.

Let us choose the convention to take the direction fromnthe observer to the source as the positive direction of velocity.consider a source s moving with velocity vsmand an observer who is stationary in frame in which the medium is also at rest.let the speednof sound wabe of angular frequency w and period to both measured by an observer at rest with respect to the medium be v.