A source of sound emits sound waves at frequency `f_(0)`. It is moving towards an observer with fixed speed `v_(s)(v_(s) lt v` where v is the speed in air). If the observer were to move towards the source with speed `v_(0)` one of the following two graphs (A and B) will give the correct variation of the frequency f heard by the observer as `v_(0)` is changed,

The variation of f with `v_(0)` is given correctly by :-

Options

A. graph A with slope `= (f_(0))/((v+v_(s))`
B. graph B with slope `= (f_(0))/((v-v_(s))`
C. graph B with slope `= (f_(0))/((v+v_(s))`
D. graph A with slope `= (f_(0))/((v-v_(s))`

Answer

D

Explanation

Apprent frequency
`f=f_(0)((V+V_(0))/(V-V_(S)))=(f_(0)V)/(V-V_(S))+(f_(0)V_(0))/((V-V_(S)))`