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Question 31213
JEE Physics · Hard

Sound Waves: Intensity MCQ

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IntensityHardQuestion 31213

Question

At distance r from a point source, intensity I ∝ 1/r². If distance doubles, dB level decreases by:
  1. A
    3 dB
  2. B
    6 dB
    Correct
  3. C
    10 dB
  4. D
    20 dB

Correct answer

6 dB

Explanation

I₂ = I₁/4. Δβ = 10 log(I₂/I₁) = 10 log(1/4) = −6 dB. Level decreases by 6 dB when distance doubles.

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