# What is the intensity of a sound which has a sound level of 35 dB?

$I \left(\mathrm{dB}\right) = 10 \log \left(\frac{I}{I} _ 0\right)$
Where ${I}_{0} = {10}^{- 12} \frac{W}{m} ^ 2$ represents the intensity just audible (correspnding to $0 \mathrm{dB}$).
$35 = 10 \log \left(\frac{I}{10} ^ \left(- 12\right)\right)$; power $10$ both sides and rearrange:
$I = 3.2 \times {10}^{-} 9 \frac{W}{m} ^ 2$