Question
Sun March 02, 2008 By:

!!!!

Expert Reply
Fri May 16, 2008

 

two sources of waves are said to be coherent if a definite phase relation ship exists between the waves.

coherent radiation is obtained by Laser action

Incoherent sources have no changing phase difference between them.

Doppler Effect:

The Doppler effect, is the change in frequency and wavelength  of a wave for an observer moving relative to the source of the waves. For waves that propagate in a medium, such as sound waves, the velocity of the observer and of the source are relative to the medium in which the waves are transmitted. The total Doppler effect may therefore result from motion of the source, motion of the observer, or motion of the medium. Each of these effects is analysed separately.

 

 

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