Two waves having same intensity $I_{0}$ and originated from two non-coherent sources superpose at a point. The average intensity at that point is . . . . . . .

Two coherent sources of light interfere and produce a fringe pattern on a screen. For the central maximum,the phase difference between the two waves will be,

For obtaining maximum contrast between the bright and dark fringes in an interference pattern, the intensities of the two light coherent sources should be

The ratio of maximum to minimum intensity in an interference pattern is $25 : 16$. Calculate the ratio of maximum to minimum amplitude.

Two coherent sources $S_1$ and $S_2$ and a screen are arranged as shown in the figure. If the distance between the two coherent sources is $n \lambda$ and the distance of the screen from the nearer coherent source $S_2$ is $D$,then the distance of the first bright fringe on the screen from the point $O$ is (where $\lambda$ is the wavelength of the light emitted by the coherent sources).

$n$ identical waves each of intensity $I_0$ interfere with each other. The ratio of maximum intensities if the interference is $(i)$ coherent and $(ii)$ incoherent is: