Two coherent sources of intensities `I_1` and `I_2` produce an interference pattern. The maximum intensity in the interference pattern will be

Options

A. `I_(1)+I_(2)`
B. `I_(1)^(2)+I_(2)^(2)`
C. `(I_(1)+I_(2))^(2)`
D. `(sqrt(I_(1))+sqrt(I_(2)))^(2)`

Answer

D

Explanation

The resultant intensity `I_(R)=I_(1)^(2)+I_(2)^(2)+2sqrt(I_(1)I_(2))cosphi`
The intensity will be maximum if `cosphi=1`
`therefore (I_(R))_(max)=I_(1)+I_(2)+2sqrt(I_(1)I_(2))=(sqrt(I_(1))+sqrt(I_(2)))^(2)`