Chapter 6 - Logarithmic Functions - 6.6 Solving Logarithmic Equations - 6.6 Exercises - Page 534: 28

$L(I)=120$ dB

$I=100=10^2$ watts per second Putting in the equation: $L(I)=10\log \frac{I}{10^{-12}}$ $L(I)=10\log \frac{ 10^2}{10^{-12}}$ $L(I)=10\log(10^2\times 10^{12} )$ $L(I)=10\log ( 10^{12})$ $L(I)=10\times 12\log 10$ $L(I)=120\log 10$ $L(I)=120$ dB