In Young's experiment,the distance between two slits is $d/3$ and the distance between the screen and the slits is $3D$. The number of fringes in $1/3 \ m$ on the screen,formed by monochromatic light of wavelength $3\lambda$,will be

Assertion: $A$ white source of light during interference forms only white and black fringes.
Reason: Width of fringe is inversely proportional to the wavelength of the light used.

$A$ beam of light consisting of two wavelengths $650 \, nm$ and $520 \, nm$ is used to illuminate the slits of a Young's double-slit experiment. The order of the bright fringe of the longer wavelength that coincides with a bright fringe of the shorter wavelength at the least distance from the central maximum is:

In an interference pattern,if the ratio of slit widths is $1:9$,find the ratio of maximum to minimum intensity.

In Young's double slit experiment,the amplitudes of the two waves incident on the two slits are $A$ and $2A$. If $I_{0}$ is the maximum intensity,then the intensity at a spot on the screen,where the phase difference between the two interfering waves is $\phi$,is:

In $Y.D.S.E.$,the separation between the two slits $S_1$ and $S_2$ is $a$,and the screen is at a distance $x$ from the slits. The light source $S$ is moving with velocity $v$ parallel to the line joining $S_1$ and $S_2$ and is at a perpendicular distance $h$ from the plane of the slits. What is the frequency of change in brightness at the central point on the screen?