MHTCET 14 May 2023 Shift 2 Solved Paper

The frequency of the sound as perceived by an observer when the source of sound is moving towards the observer is given by the Doppler Effect. According to the Doppler Effect, if a source of sound with the frequency f0 (real frequency) moves towards a stationary observer with velocity vs and the sound travels with a velocity v , then the apparent frequency f′ heard by the observer is given by:
f′=f0(‌

v+v0

v−vs

)
Here, v0 is the velocity of the observer which is zero and vs=‌

v

10

since the source of sound is moving at one tenth the speed of sound. Substituting these values back into the equation, we get:
‌f′=f0(‌

v

v−‌ v 10

)
‌f′=f0(‌

v

9v 10

)
‌f′=f0(‌

10

9

)
Hence, the ratio of the apparent frequency to the real frequency is 10:9, which corresponds to Option A.