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

Options

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

Answer

c

Explanation

In the second case,
`I = I_(0) + I_(0) + 2 I_(0) cos 0^(@)`
or `I = 4 I_(0)`
In the second case
`I' = I_(0) + I_(0) = 2 I_(0)`
`:. (I)/(I') = (4 I_(0))/(2 I_(0)) = (2)/(1)`