Interference fringes were produced in Young's double slit experiment using light of wavelength $5000 \, Å$. When a film of material $2.5 \times 10^{-3} \, cm$ thick was placed over one of the slits, the fringe pattern shifted by a distance equal to $20$ fringe widths. The refractive index of the material of the film is

In a double slit experiment, instead of taking slits of equal widths, one slit is made twice as wide as the other. Then in the interference pattern

The slits in a double-slit interference experiment are illuminated by orange light $(\lambda = 600 \ nm)$. $A$ thin transparent plastic sheet of thickness $t$ is placed in front of one of the slits. The number of fringes $(N)$ shifting on the screen is plotted versus the refractive index $\mu$ of the plastic in the graph shown. The value of $t$ is

The figure shows a double-slit experiment. Each slit has a width $W$. $A$ thin glass slab of thickness $\delta$ and refractive index $\mu$ is placed in front of one of the slits. The intensity at the central point $C$ is measured as a function of the thickness $\delta$. At what thickness $\delta$ will the intensity at $C$ be minimum?

To make the central fringe appear at the centre $O$ of the screen,a mica sheet of refractive index $\mu = 1.5$ is introduced in front of one of the slits. Choose the correct statement.

In a double slit experiment,when a thin film of thickness $t$ having refractive index $\mu$ is introduced in front of one of the slits,the maximum at the centre of the fringe pattern shifts by one fringe width. The value of $t$ is ($\lambda$ is the wavelength of the light used).