Question

Intensity level of a sound of intensity $I$ is $30dB$. The ration $I/I_o$ is ($I_o$ is the threshold of hearing)

• A. $1000$
• B. $3000$
• C. $300$
• D. $30$

Answer 1

The correct option is A $1000$

Intensity level = $10log\left(\frac{I}{I_0}\right)$

Given , intensity level = $30$ $dB$.

$30$ = $10log\left(\frac{I}{I_0}\right)$

$3$ = $log\left(\frac{I}{I_0}\right)$

${10}^3$ = $\left(\frac{I}{I_0}\right)$

Hence , the required ratio $\frac{I}{I_0}$ is equal to $1000$ .