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

Two coherent sources produce interference fringes with an intensity ratio of $81:1$. Find the ratio of the maximum to the minimum intensity in the interference pattern.

The phenomenon of interference is shown by

Two coherent point sources $S_1$ and $S_2$ are separated by a small distance '$d$' as shown. The fringes obtained on the screen will be

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).

Two identical light waves having phase difference $\phi$ propagate in the same direction. When they superpose,the intensity of the resultant wave is proportional to