Question

Two coherent monochromatic light beams of intensities $I$ and $41$ are superposed. The maximum and minimum possible intensities in the resulting beam are

• A. $51$ and $I$`
• B. $51$ and $31$
• C. $91$ and $I$
• D. $91$ and $31$

Answer 1

The correct option is C $91$ and $I$

maximum intensity is $(\sqrt{I_1}+\sqrt{I_2}{)}^2=(\sqrt{4I}+\sqrt{I}{)}^2=9I$
minimum intensity is $(\sqrt{I_1}-\sqrt{I_2}{)}^2=(\sqrt{4I}-\sqrt{I}{)}^2=I$
option $C$ is correct