Two coherent monochormatic light source are located at two vertices of an equilateral trangle. If the intensity due to each of the source independently is `1Wm^(-2)` at the third vertex. The resultant intensity due to both the sources at that point (i.e at the third vertex) is (in `Wm^(-2)` )

Options

A. zero
B. `sqrt(2)`
C. 2
D. 4

Answer

D

Explanation

Intensity `I_(1)=I_(2)=1Wm^(-2)`
So, resultant intensity at third vertex
`I=(sqrt(I_(1))+sqrt(I_(2)))^(2)=(sqrt(1)+sqrt(1))^(2)=(1+1)^(2)=4Wm^(-1)`