Two coherent light beams of intensities I and 4 I are superimposed. The maximum and minimum possible intensities in the resulting pattern are:

9 I and I

The correct answer is Option (3) → 9 I and I

Maximum intensity ($I_{max}$) is,

$I_{max}=\left(\sqrt{I_1}+\sqrt{I_2}\right)^2$

$=\left(\sqrt{I}+\sqrt{4I}\right)^2=9I$

Maximum intensity ($I_{max}$) is,

$I_{max}=\left(\sqrt{I_1}-\sqrt{I_2}\right)^2$

$=\left(\sqrt{I}-\sqrt{4I}\right)^2=I$