Volume and decibels When the volume control on a stereo system is increased, the voltage across a loudspeaker changes from $V_{1}$ to $V_{2},$ and the decibel increase in gain is given by
$$
\mathrm{db}=20 \log \frac{V_{2}}{V_{1}}
$$
Find the decibel increase if the voltage changes from 2 volts to 4.5 volts.