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

Let `I_(1)=I` and `I_(2)=4I`
We known that Intensity `prop("amplitude")^(2)`
Let `I prop a^(2)`
`:. I_(1)prop a^(2)` and `:. I_(2)prop (2a)^(2)`
Maximum amplitude `=a+2a=3a`
`:. I_(max)prop(3a)^(2)rArrI_(max)prop9a^(2)`
`rArr I_(max)prop9I`
Minimum amplitude `=2a-a=a`
`:.I_(min)propa^(2)rArrI_(min)propI`
(c) is the correct option.