Statement I: A person is standing near a railway track. A train is moving on the track. As the train is approaching the person, apparent frequency keeps on increasing and when the train has passed the person, then apparent frequency keeps on decreasing.
Statement II: When train is approaching the person then,
`f=f_0[(c )/(c-u)]`
and when train is moving away from person
`f=f_0[(c )/(c+u)]`
Here, c is velocity of sound u is velocity of train and `f_0` is original frequency of whistle.

Options

A. Statement I is true, Statement II is true: Statement II is a correct explanation for statement I.
B. Statement I is true, Statement II is true, Statement II is NOT a correct explanation for Statement I.
C. Statement I is true, Statement II is false
D. Statement I is falce: Statement II is true

Answer

D

Explanation

`f=f_0[(c+o)/(c-u)]`
`f=f_0[(c )/(c+u)]`
So, when the train is approaching, frequency has constant value given by
`f_0[(c )/(c-u)]`