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A bat moving at 10 ms − 1 towards a wall sends a sound signal of 8000 Hz towards it. On reflection it hears a sound of frequency f . The value of f in Hz is close to ( speed of sound = 320 ms − 1 )

Options

  1. A8258
  2. B8424
  3. C8000
  4. D8516

Correct answer

D. 8516

Step-by-step solution

We can assume that reflected wave is due to image of B coming with same speed in opposite direction Observer f = v + 10 v - 10 × f 0 = 320 + 10 320 - 10 × 8000 = 330 310 × 8000 = 33 31 × 8000 = 8516 H z

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