Physics - Sound Wave Question with Solution | TestHub

The resultant intensity is given by $I_{\mathrm{net} }=I_1+I_2+2\sqrt{I_1}\sqrt{I_2}\cos \varphi$

Now, for ${\mathit{I}}_{\max }$, phase angle is $\varphi =0$ and for $I_{\min }$, phase angle is $\varphi =\pi$.

Thus, $I_{\max }={\left(\sqrt{I_1}+\sqrt{I_2}\right)}^2={\left(\sqrt{9I}+\sqrt{4I}\right)}^2=25I$

And $I_{\min }={\left(\sqrt{I_1}-\sqrt{I_2}\right)}^2={\left(\sqrt{9I}-\sqrt{4I}\right)}^2=I$

The difference of resultant intensities is $I_{\max }-I_{\min }=25I-I=24I$