Q. In a Young’s double-slit experiment, constructive interference is produced at a certain point P. The intensities of light at P due to the individual sources are 4 and 9 units. The resultant intensity at point P will be
A) 13 units
B) 25 units
C) $\sqrt{97}$ units
D) 5 units
Explanation
(b) $I = I_{1} + I_{2} + 2\sqrt{I_{1}I_{2}}\cos{0{^\circ}}$
$\ = 4 + 9 + 2\sqrt{4 \times 9}$
$= 25\ units$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.