To demonstrate the phenomenon of interference,we require two sources which emit radiation of

Light from two coherent sources of the same amplitude $A$ and wavelength $\lambda$ illuminates the screen. The intensity of the central maximum is $I_{0}$. If the sources were incoherent,the intensity at the same point will be

Path difference between two light waves at a point $P$ for constructive interference will be

In the phenomenon of interference:

If the wavelength of light is $4000 \text{ Å}$, then the number of waves in $1 \text{ mm}$ length will be . . . . . . -

Two coherent sources of intensity ratio $9:4$ produce interference. The intensity ratio of maxima and minima of the interference pattern is