If the path difference of the point on the screen from two coherent sources is constant, what is the shape of the trajectory of the point on the screen?

In Young's double slit experiment,the wavelength of red light is $7800\,\mathring{A}$ and that of blue light is $5200\,\mathring{A}$. The value of $n$ for which the $n^{th}$ bright band due to red light coincides with the $(n + 1)^{th}$ bright band due to blue light is:

This question has Statement-$1$ and Statement-$2$. Of the four choices given after the Statements,choose the one that best describes the two Statements.
Statement-$1$: In Young's double slit experiment,the number of fringes observed in the field of view is small with longer wavelength of light and is large with shorter wavelength of light.
Statement-$2$: In the double slit experiment,the fringe width depends directly on the wavelength of light.

In a Young's double-slit experiment,the fringe width is $0.8 \, mm$ when light of wavelength $6000 \, \mathring{A}$ is used,and the screen is at a distance of $2.5 \, m$. If the experiment is performed in a liquid with a refractive index of $1.6$,the new fringe width will be.....$mm$.

In Young's double slit experiment,a mica sheet of thickness $t$ and refractive index $\mu$ is introduced in the path of the ray from the first source $S_1$. By what distance will the fringe pattern be displaced?

In a Young's double-slit experiment,$92$ fringes are observed when sodium light $(\lambda = 5898 \, \mathring A)$ is used. If light of wavelength $\lambda = 5461 \, \mathring A$ is used instead,how many fringes will be observed?