Q. Light from two coherent sources of the same amplitude $A$ and wavelength $\lambda$ illuminates the screen. The intensity of the central maximum is $I_{0}.$ If the sources were incoherent, the intensity at the same point will be
A) $4I_{0}$
B) $2I_{0}$
C) $I_{0}$
D) $I_{0}/2$
Explanation
(d) For two coherent sources, $I_{1} = I_{2}$
$I_{\max} = \left( A_{1} + A_{2} \right)^{2} = \left( \sqrt{I_{1}} + \sqrt{I_{2}} \right)^{2}$
This is given as $I_{0}$ for maximum and zero for minimum. If there are two noncoherent sources, there will be no maximum and minimum intensities. Instead of all the intensity $I_{0}$ at maximum and zero foe minimum, it will be just $I_{0}/2$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.