Question

The threshold of sound is ${10}^{-12}W{m}^{-2}$.What is the intensity level of sound whose intensity is ${10}^{-8}W{m}^{-2}$?

• A. 40 db
• B. 8db
• C. 12 db
• D. 20 db

Answer 1

The correct option is A 40 db

Intensity in decibels is expressed as $I\left(dB\right)=10log\left(\frac{I}{I_0}\right)$

where $I_0$ is the threshold intensity of sound.

Thus $I\left(dB\right)=10log\left(\frac{{10}^{-8}}{{10}^{-12}}\right)=40$