In a Young's double slit experiment,the angular width of a fringe is $0.35^{\circ}$ on a screen placed at $2\,m$ away for a particular wavelength of $450\,nm$. The angular width of the fringe,when the whole system is immersed in a medium of refractive index $7/5$,is $\frac{1}{\alpha}$. The value of $\alpha$ is ..............

In a Young's double-slit interference experiment,a monochromatic beam of light is used to form fringes on a screen. When a thin mica sheet is placed in the path of one of the interfering beams,then...

In a Young's double slit experiment,two slits are illuminated with light of wavelength $\lambda = 800 \, nm$. The line joining $A_1 P$ is perpendicular to $A_1 A_2$ as shown in the figure. If the first minimum is detected at $P$,the value of slit separation '$a$' will be $......... \, mm$. The distance of the screen from the slits is $D = 5 \, cm$.

Given below are two statements:
Statement $I$: In a Young's double slit experiment, the angular separation of fringes will increase as the screen is moved away from the plane of the slits.
Statement $II$: In a Young's double slit experiment, the angular separation of fringes will increase when a monochromatic source is replaced by another monochromatic source of higher wavelength.
In the light of the above statements, choose the correct answer from the options given below:

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 a Young's double slit experiment illuminated by monochromatic light,the intensity reaching the screen from each slit is $I$. What is the resultant intensity at a point where the phase difference is $60^{\circ}$?