A Young’s double slit apparatus has slits separated by 0.28 mm and a screen 48 cm away from the slits. The whole apparatus is immersed in water and the slits are illuminated by the red light (λ = 700 nm in vacuum). Find the fringe-width of the pattern formed on the screen.

Question

Philoid · Accepted Answer

Given, separation between the slits

The distance between the screen and the slit,

Wavelength of light,

refractive index of water,

Now, the fringe width is given by

But as the light is passing through water, its wavelength changes.

Therefore,