Decibels: a 100-fold change in intensity
If the intensity of a sound increases by a factor of 100, the sound level increases by:
Answer C: explanation for every choice
A
This takes log₁₀(100) = 2 but forgets to multiply by 10.
B
This is the change for a 10-fold increase in intensity.
C
Correct. Δβ = 10 log(100) = 10 × 2 = 20 dB.
D
The decibel scale is logarithmic, not linear.
Takeawayβ = 10 log(I/I₀). Each 10-fold increase in intensity adds 10 dB.
Equation usedSound level
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