In Young's double-slit experiment, the two slits act as coherent sources of equal amplitude `A` and of wavelength `lamda`. In another experiment with the same set-up the two slits are sources of equal amplitude `A ` and wavelength `lamda`, but are incoherent. The ratio of the intensity of light at the midpoint of the screen in the first case to that in the second case is....

Options

A. 4
B. 2
C. 1
D. `0.5`

Answer

B

Explanation

For coherent sources
`I_(1) = 4I_(0)cos^(2)phi//2=4I_(0)` For incoherent sources
`I_(2)=I_(0)+I_(0)=2I_(0) , :. (I_(1))/(I_(2)) =2`