Young’s double slit experiment is first performed in air and then in a medium other than air. It is found that ${8^{th}}$ bright fringe in the medium lies where ${5^{th}}$ dark fringe lies in air. The refractive index of the medium is nearly.

If the amplitudes of two interfering waves are in the ratio 2:5, what is the ratio of the maximum to minimum intensity in the interference pattern?

Two waves originating from source ${S_1}\;and\;{S_2}$ having zero phase difference and common wavelength $\lambda$ will show complete destructive interference at a point $P$, is$({S_1}P - {S_2}P) =$

The intensity of gamma radiation from a given source is $I$. On passing through $36\;mm$ of lead, it is reduced to ${I/8}$. The thickness of lead which will reduce the intensity to ${I/2}$ will be

Two identical light waves, propagating in the same direction, have a phase difference $\delta$. After they superpose, the intensity of the resulting wave will be proportional to

In a Fresnel’s diffraction arrangement, the screen is at a distance of 2 meter from a circular aperture. It is found that for light of wavelengths ${{\lambda _1}\;and\;{\lambda _2}}$, the radius of ${4^{th}}$ zone for ${{\lambda _1}}$ coincides with the radius of ${5^{th}}$ zone for ${{\lambda _2}}$. Then the ratio ${{\lambda _1}:{\lambda _2}}$ is

Colours of thin films result from

Or

On a rainy day, a small oil film on water show brilliant colours. This is due to

Light propagates $2\;cm$ distance in glass of refractive index 1.5 in time ${t_0}$. In the same time ${t_0}$, light propagates a distance of $2.25\;cm$ in a medium. The refractive index of the medium is

In an interference pattern the position of zeroth order maxima is $4.8\;{\rm{mm}}$ from a certain point ${\rm{P}}$ on the screen. The fringe width is $0.2\;{\rm{mm}}$. The position of second maxima from point ${\rm{P}}$ is

In Young’s double slit experiment the wavelength of light was changed from $7000\;\mathop {{\rm A}\;to\;}\limits^ \circ \;3500\;\mathop {\rm A}\limits^ \circ$. While doubling the separation between the slits which of the following is not true for this experiment

If fringe width is $0.4{\rm{ }}mm$ the distance between fifth bright and third and third dark band on same side is