Question

A sound has an intensity of $2\times {10}^{-8}W\text{/}{m}^2$ . Its intensity level in decibels is $\left({\log }_{10}2=0.3\right)$

• A. 23
• B. 3
• C. 43
• D. 4.3

Answer 1

Answer: (C)

$L=10{\log }_{10}\left(\frac{I}{I_0}\right)$ $\therefore$ $L=10{\log }_{10}\left(\frac{2\times {10}^{-8}}{{10}^{-12}}\right)$ $(\because I_0={10}^{-12}W\text{/}{m}^2)$ $L=10{\log }_{10}(2\times {10}^4)$ $L=10[{\log }_{10}2+{\log }_{10}{(10)}^4]$ $L=10(4.3)$ $L=43decibel$