1. Tardigrade
  2. Question
  3. Physics
  4. In an interference, the intensity of two interfering waves are I and 4I respectively. They produce intensity at two points A and B with phase angle of π/2 and π respectively. Then difference in between them is

Question Error Report

Thank you for reporting, we will resolve it shortly

Back to Question

Q. In an interference, the intensity of two interfering waves are $I$ and $4I $ respectively. They produce intensity at two points A and B with phase angle of $\pi$/2 and $\pi$ respectively. Then difference in between them is

AIIMSAIIMS 2011Wave Optics

Solution:

Resultant intensity,
$I=I_{1}+I_{2}+2\sqrt{I_{1}I_{2}}cos\, \phi$
Here, $I_{1}=I,I_{2}=4I,\phi_{1}=\frac{\pi}{2}$ and $\phi_{2}=\pi$
At A intensity,
$I_{A}=I+4I+2\sqrt{4I^{2}}\,cos \frac{\pi}{2}=5I$
At B intensity,
$I_{B}=I+4I+2\sqrt{4I^{2}}cos \pi=5I-4I=I$
Therefore, difference between intensities is
$I_{A}-I_{B} = 5I-I = 4I$