If a source emitting waves of frequency f moves towards an observer with a velocity `(v)/(4)` and the observer moves away from the source with a velocity `(v)/(6)`, the apparent frequency as heard by the observer will be (v=velocity of sound)

Options

A. `14/15 f`
B. `14/9 f`
C. `10/9 f`
D. `2/3 f`

Answer

C

Explanation

When source and observer both are moving in the same direction and observer is ahead of source, then apparent frequency,
`f' = (v -v_(0))/(v -v_(s)) f`
`= (v - (v)/(6))/(v - (v)/(4)) = ((5v)/(6))/((3v)/(4)) f = (10)/(9) f`