Question

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.

• A. I
• B. 2I
• C. 4I
• D. 5I

Answer 1

Answer: (C)

4I

Net intensity after interference of waves with phase difference $\varphi$

$I_{net}=I_1+I_2+2\sqrt{I_1{I}_2}cos\varphi$

Thus $I_{ne{t}_1}(\varphi =\pi /2)=5I$

$I_{ne{t}_2}(\varphi =\pi )=I$

Thus, the difference between them $=4I$