Two coherent monochromatic light beams of intensities I and 4I are superposed. The maximum and minimum possible intensities in the resulting beam are

Options

A. (a) `5I` and `I`
B. (b) `5I` and `3I`
C. (c) `9I` and `I`
D. (d) `9I` and `3I`

Answer

C

Explanation

`I_(max)=(sqrt(I_1)+sqrt(I_2))^2=(sqrtI+sqrt(4I))^2=9I`
`I_(min)=(sqrt(I_1)-sqrt(I_2))^2=(sqrtI-sqrt(4I))^2=I`