Question

Two monochromatic coherent light beans $A$ and $B$ have intensities $L$ and $\frac{L}{4}$ respectively.If these beams are super-posed, the maximum and minimum intensities will be

• A. $\frac{9L}{4},\frac{L}{4}$
• B. $\frac{5L}{4},0$
• C. $\frac{5L}{2},0$
• D. $2L,\frac{L}{2}$

Answer 1

The correct option is A $\frac{9L}{4},\frac{L}{4}$

$I_{maximum}={(\sqrt{L}+\frac{\sqrt{L}}{4})}^2=\frac{9L}{4}$
$I_{minimum}={(\sqrt{L}-\frac{\sqrt{L}}{4})}^2=\frac{L}{4}$