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MHTCET 10 May 2024 Shift 1 Paper

Question : 29 of 150

Marks: +1, -0

\mathrm{V}_{1}

F_{1}

\mathrm{V}_{1}

F_{2}

\frac{F_{1}}{F_{2}}=2

\frac{V}{V_{1}}

Solution:

Concept:

Doppler effect for a moving observer and a stationary source.

Explanation:

When the observer moves towards the stationary source with velocity

V_1

, the apparent frequency is:

F_1 = f \frac{V+V_1}{V}

When the observer moves away from the source with the same velocity, the apparent frequency is:

F_2 = f \frac{V-V_1}{V}

Given

\frac{F_1}{F_2} = 2

, we get:

\frac{V+V_1}{V-V_1} = 2

Cross-multiplying:

V+V_1 = 2V - 2V_1

Rearranging:

3V_1 = V

Therefore:

\frac{V}{V_1} = 3

Answer:

Option B, i.e.

3

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