In Young's double slit experiment,the amplitudes of two sources are $3a$ and $a$ respectively. The ratio of intensities of bright and dark fringes will be (in $:1$)

In a double slit experiment,when the distance between slits is increased $10$ times,while their distance from the screen is halved,then the fringe width

$A$ beam of electrons is used in a $YDSE$ experiment. The slit width is $d$. When the velocity of the electrons is increased,then

If the source of light used in a Young's double slit experiment is changed from red to violet:

In Young's double-slit experiment,an interference pattern is obtained on a screen by light of wavelength $6000 \ \mathring A$,coming from coherent sources $S_1$ and $S_2$. At a certain point $P$ on the screen,the third dark fringe is formed. Then the path difference $S_1P - S_2P$ in microns is:

In Young's double slit experiment,the two slits are $0.6 \; mm$ apart. The interference pattern is observed on a screen at a distance of $80 \; cm$ from the slits. The first dark fringe is observed on the screen directly opposite to one of the slits. The wavelength of light is $\dots \; nm$.