Concepts Of Physics MCQ Edition [Volume 1]PhysicsSound Waves
A small source of sound travels on a circle as shown in the figure, while an observer is located at O . Suppose ₁ , ₂ , and ₃ are the frequencies detected by the observer when the source is at points A , B , and C , respectively.
Options
- A₁ > ₃ > ₂
- B₁ > ₂ > ₃
- C₁ = ₂ > ₃
- D₂ > ₃ > ₁
Correct answer
D. ₂ > ₃ > ₁
Step-by-step solution
According to the Doppler effect, the apparent frequency increases when the source approaches the observer and decreases when it recedes. From the given figure, the arrow on the circular path indicates that the source is moving in a clockwise direction. At point B , the velocity of the source is directed towards the observer at O . Since the source is approaching the observer, the apparent frequency ₂ is greater than the actual frequency ₀ ( ₂ > ₀ ). At point A , the velocity of the source is directed away from the