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. 5I and I
B. 5I and 3I
C. 9I and I
D. 9I and 3I

Answer

C

Explanation

`I_(max)=(sqrt(I_(1))+sqrt(I_(2)))^(2)=(sqrt(4I)+sqrt(I))^(2)=9I`
`I_("min")=(sqrt(I_(1))-sqrt(I_(2)))^(2)=(sqrt(4I)-sqrt(I))^(2)=I`