In a Young's double slit experiment,the angular width of a fringe formed on a distant screen is $1^{\circ}$. The wavelength of the light used is $6280 \; \mathring{A}$. The distance between the two coherent sources is $...........\,mm$.

If the Young's double slit experiment is performed with white light,then which of the following is not true?

Two coherent sources $P$ and $Q$ produce interference at point $A$ on the screen,where a dark band is formed between the $4^{\text{th}}$ bright band and the $5^{\text{th}}$ bright band. The wavelength of the light used is $6000 \text{ Å}$. The path difference between $PA$ and $QA$ is:

In $YDSE$ setup,light of wavelength $640 \, nm$ is used with $d = 0.8 \, mm$ and $D = 1 \, m$. If intensity at central maximum is $I_0$ and its position is $y = 0$,then:

Using monochromatic light of wavelength $\lambda$,an experimentalist sets up the Young's double slit experiment in three ways as shown. If she observes that $y = \beta'$,the wavelength of light used is.....$nm$

The width of one of the two slits in a Young's double slit experiment is $4$ times that of the other slit. The ratio of the maximum to the minimum intensity in the interference pattern is: (in $: 1$)