Physics - Wave on String Question with Solution | TestHub

Two beams of light having intensities I and $4\mathrm{I}$ interfere to produce a fringe pattern on a screen. The phase difference between the beams is $\pi /2$ at point $\mathrm{A}$ and $\pi$ at point $\mathrm{B}$. Then the difference between the resultant intensities at $A$ and $B$ is