Two slits are separated by $0.3\, mm$. $A$ beam of $500\, nm$ light strikes the slits producing an interference pattern. Find the number of maxima observed in the angular range $-30^{\circ} < \theta < 30^{\circ}$.

In a Young's double slit experiment,the source $S$ and the two slits $A$ and $B$ are vertical,with slit $A$ above slit $B$. The fringes are observed on a vertical screen $K$. The optical path length from $S$ to $B$ is increased very slightly (by introducing a transparent material of higher refractive index) and the optical path length from $S$ to $A$ is not changed. As a result,the fringe system on $K$ moves:

In Young's double slit experiment,if the widths of the slits are in the ratio $4 : 9$,the ratio of the intensity at maxima to the intensity at minima will be

Two coherent sources of light are placed at points $(-\frac{5a}{2}, 0)$ and $(+\frac{5a}{2}, 0)$. The wavelength of the light is $\lambda = \frac{4a}{3}$. How many maxima will be obtained on a planar circle of large radius with its center at the origin?

In a double slit experiment,the distance between slits is increased $10$ times,whereas their distance from the screen is halved. The fringe width:

If yellow light in the Young's double slit experiment is replaced by red light,the fringe width will