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

If the ratio of the amplitudes of two interfering sources is $3 : 5$,then the ratio of the intensity of maxima and minima in the interference pattern will be

If the wavelength of light is $4000 \mathring A$,then the number of waves in $1 \ mm$ length 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 coherent sources whose intensity ratio is $64: 1$ produce interference fringes. The ratio of intensities of maxima and minima is

Two coherent sources have different intensities. They produce an interference pattern. If the ratio of maximum to minimum intensities is $25:1$,find the ratio of the intensities of the sources.