Q. Two coherent sources of intensities, $I_{1}$ and $I_{2}$ produce an interference pattern. The maximum intensity in the interference pattern will be
A) $I_{1} + I_{2}$
B) $I_{1}^{2} + I_{2}^{2}$
C) $\left( I_{1} + I_{2} \right)^{2}$
D) $\left( \sqrt{I_{1}} + \sqrt{I_{2}} \right)^{2}$
Explanation
(d) Resultant intensity $I_{R} = I_{1} + I_{2} + 2\sqrt{I_{1}I_{2}}\cos\phi$
For maximum $I_{R},\ \phi = 0{^\circ}$
$\Rightarrow I_{R} = I_{1} + I_{1} + 2\sqrt{I_{1}I_{2}} = \left( \sqrt{I_{1}} + \sqrt{I_{2}} \right)^{2}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.