In Young's double slit experiment,how many maximas can be obtained on a screen (including the central maximum) on both sides of the central fringe if $\lambda = 2000\,{\mathring A}$ and $d = 7000\,{\mathring A}$?

In an interference pattern,the fringe width is $\beta$. If the frequency of the source is doubled,the fringe width becomes .....

In the Young's double slit experiment,the ratio of intensities of bright and dark fringes is $9$. This means that

In Young's double slit experiment,the two slits act as coherent sources of equal amplitude $A$ and wavelength $\lambda$. In another experiment with the same setup,the two slits are of equal amplitude $A$ and wavelength $\lambda$ but are incoherent. The ratio of the intensity of light at the mid-point of the screen in the first case to that in the second case is

In Young's double slit experiment, two slits are illuminated with light of wavelength $\lambda$. The line joining $A_1P$ is perpendicular to $A_1A_2$. If the first minimum is detected at $P$, the value of slit separation '$a$' will be (where $D$ is the distance between the source and the screen):

In Young's double slit experiment,we get $60$ fringes in the field of view using monochromatic light of wavelength $4000 \; \mathring{A}$. If we use monochromatic light of wavelength $6000 \; \mathring{A}$,then the number of fringes obtained in the same field of view is