Manipal Entrance Test 2020 Physics Paper

Generalized formula for apparent frequency is fa=(‌

v±vo

v∓vs

)f0
According to the question source is stationary, vs=0
fa=f′=(‌

v±vo

v

)f0
Observer is moving towards the source
⇒‌‌fa=f′(‌

v+vo

v

)f
where, v= speed of the wave
vo= speed of the observer
f= original frequency of the source