Answers

2014-05-21T20:52:24+05:30
Doppler effect is an increase (or decrease) in the frequency of sound, light, or other waves as the source and observer move towards (or away from) each other. The effect causes the sudden change in pitch noticeable in a passing siren, as well as the red shift seen by astronomers.
                          λO = λS(c − vS)/(c − vO)
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