If a torch is used in place of monochromatic light in Young's experiment,what will happen?

In Young's double slit experiment,if the wavelength of the light used is doubled and the distance between the two slits is halved,the resultant fringe width becomes $n$ times the initial fringe width. Find the value of $n$.

In Young's double slit experiment,the ratio of intensity of maxima and minima in the interference experiment is $25 : 9$. The ratio of the widths of the two slits is:

In Young's double-slit experiment,the fringes are displaced by a distance $x$ when a glass plate of refractive index $1.5$ is introduced in the path of one of the beams. When this plate is replaced by another plate of the same thickness,the shift of fringes is $(3/2)x$. The refractive index of the second plate is

In Young's double-slit experiment,we get $10$ fringes in the field of view using monochromatic light of wavelength $4000 \text{ } \mathring{A}$. If we use monochromatic light of wavelength $5000 \text{ } \mathring{A}$,then the number of fringes obtained in the same field of view is

Light of wavelength $520\, nm$ passing through a double slit produces an interference pattern of relative intensity versus deflection angle $\theta$ as shown in the figure. The separation $d$ between the slits is