The Intensity of sound of loudness level 60dB  is  $n\times {10}^{-4}watt/m^2$ . Find n.

$$\begin{gathered} \beta =10{\log }_{10}\left(\raisebox{1ex}{$I$}\!\left/ \!\raisebox{-1ex}{$I_0$}\right.\right) \\ \Rightarrow 60=10{\log }_{10} \left(\raisebox{1ex}{$I$}\!\left/ \!\raisebox{-1ex}{$I_0$}\right.\right) \\ \Rightarrow I=I_0\times {10}^6 \\ \Rightarrow I={10}^{-12}\times {10}^6 \\ \Rightarrow I={10}^{-6}watt/m^2 \\ \Rightarrow I=0.01\times {10}^{-4}watt/m^2 \end{gathered}$$