Exam-style question
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What is the decibel level of a sound that has an intensity of 0.001 W/m²?.
- A.30 dB
- B.90 dB
- C.100 dB
- D.120 dB
Model answer
What a good answer should say
- 90 dB
Explanation
Why this works
The formula for sound intensity level in decibels is L = 10 log10(I/I0), where I0 is the reference intensity (1.0 x 10^-12 W/m²). Substituting I = 0.001 W/m² gives L = 10 log10(0.001/1.0 x 10^-12) = 10 log10(10^9) = 90 dB.
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