Two coherent monochromatic light beams of intensities I and 4I are superposed. The maximum and minimum possible intensities in the resulting beam are
Answer & explanation
Correct answer: option 3
$I_{\max }=\left(\sqrt{I_1}+\sqrt{I_2}\right)^2=(\sqrt{I}+\sqrt{4 I})^2=9 I$
$I_{\min }=\left(\sqrt{I_1}-\sqrt{I_2}\right)^2=(\sqrt{I}-\sqrt{4 I})^2=I$