If Fresnel's bi prism experiment as held in water in spite of air,  what will be the effect on the fringe width?

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

The Young's double slit experiment is performed with blue light and green light of wavelengths $4360 \mathrm{\AA }$ and $5460 \mathrm{\AA }$ respectively. If $X$ is the distance of $4^{th}$ maxima from the central one, then

In a Young's double slit experiment with light of wavelength $\mathrm{\lambda ,}$ the separation of slits is $d$ and distance of screen is $D$ such that $D\gg d\gg \lambda$ . If the Fringe width is $\beta$ , the distance from point of maximum intensity to the point where intensity falls to half of the maximum intensity on either side is:

In Newton's rings experiment, obtain an expression for the radius of the ${\mathrm{n}}^{\mathrm{th}}$ dark ring.

Two point sources $S_1$ and $S_2$ separated by a distance $10 \mu \mathrm{m}$ emit light waves of wavelength $4 \mu \mathrm{m}$ in phase. A circular wire of radius $40 \mu \mathrm{m}$ is placed around the sources as shown in figure, then ($O$ is the centre of the circle and $O{S}_1=O{S}_2$)