The correct formula for fringe visibility is

For a distinct interference pattern to be observed,the necessary condition is that the ratio of the intensity of light emission by both sources should be

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

To observe a stationary interference pattern formed by two light waves,it is not necessary that they must have :

The total energy carried by a light wave when it travels from a rarer to a non-reflecting and non-absorbing medium:

Two light rays having the same wavelength $\lambda$ in vacuum are in phase initially. Then the first ray travels a path $L_1$ through a medium of refractive index $\mu_1$,while the second ray travels a path of length $L_2$ through a medium of refractive index $\mu_2$. The two waves are then combined to observe interference. The phase difference between the two waves is