Chapter 6 - Logarithmic Functions - 6.6 Solving Logarithmic Equations - 6.6 Exercises - Page 534: 32

$I=0.3162\text{ watt/m}^2$

$L(I)=115$ dB Putting in the equation: $L(I)=10\log\frac{I}{10^{-12}}$ $115=10\log (I\times 10^{12})$ $\frac{115}{10}=\log(10^{12}I)$ $\log(10^{12}I)=11.5 $ $10^{12}I=10^{11.5}$ $I=\frac{10^{11.5}}{10^{12}}=10^{-0.5}=0.3162$ $\frac{watt}{m^2}$