In a double slit experiment performed in air, the angular width of a fringe is found to be $0.15^{\circ}$ on a screen placed 80 cm away. The wavelength of light is used 490 nm . The angular width of the fringe, if the entire apparatus is immersed in a medium of refractive index $\frac{5}{3}$ is

In Young's double slit experiment for what order does the wavelength of red light $(\lambda=780 \mathrm{~nm})$ coincide with $(n+1)$ th order of blue light $(\lambda=520 \mathrm{~nm})$ ?

The angular width of a fringe in a double slit experiment is found to be $0.2^{\circ}$ on a screen 1 m away the wavelength of light used is 600 nm . The change in angular width of the fringe, if the entire measurement system is immersed in water is [use refractive index of water as $4 / 3$ ]

A Young's double slit experiment apparatus has slits separated by 0.2 mm and a screen 60 cm away from the slits. The whole apparatus is immersed in a liquid medium of refractive index $11 / 9$ and the slits are illuminated with green light ( $\lambda=550$ nm in vacuum). Find the fringe width of the pattern formed on the screen.