Question

In expressing sound intensity, we take ${10}^{-12}W/m^2$ as the reference level. For ordinary conversation, the intensity level is about ${10}^{-6}W/m^2$. Expressed in decibel, this is

• A. ${10}^6$
• B. $6$
• C. $60$
• D. ${\log }_e\left({10}^6\right)$

Answer 1

Answer: (C)

$60$

wkt, $IL=10{\log }_{10}\left[\frac{I}{Io}\right]$

where, $I={10}^{-6}$ and $I_o={10}^{-12}$

Substituting the values,

$\therefore IL=10{\log }_{10}\left[\frac{{10}^{-6}}{{10}^{-12}}\right]$

$=10{\log }_{10}\left[{10}^6\right]$

$=6\times 10{\log }_{10}10$

$\therefore dB=60dB$