An engine of a moving train emits a whistle of frequency n. if n' is the apparent frequency of the sound heard by a passenger in the train, then

Options

A. `n'=zero`
B. `n'gtn`
C. `n'ltn`
D. `n'=n`

Answer

D

Explanation

`n.=n`
In fact, there is no relative motion between the source and the observer, Doppler effect does not occur.