Question

In Young’s double slit experiment, the two slits act as coherent sources of light waves of equal amplitude $A$ and of wavelength $\lambda$. In another experiment with the same setup, the two slits are source of light waves of equal amplitude $A$ and wavelength $\lambda$ but are incoherent. 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:

• A. $2:1$
• B. $1:2$
• C. $4:1$
• D. $2:4$

Answer 1

The correct option is A $2:1$

The intensity at central maximum is four times the individual wave intensity if waves are coherent.
The intensity at central maximum is two times the individual wave intensity if waves are incoherent..