In Young's Double Slit Experiment, the fringe width in air is 2.4 μm. If the experiment is performed in a medium of refractive index 1.2, find the new fringe width.

The fringe width in Young's Double Slit Experiment is:

β = λD/d

where:

• λ = wavelength
• D = distance of screen from slit
• d = separation between slits

When the entire setup is immersed in a medium having refractive index μ, the wavelength changes according to:

λ' = λ/μ

Therefore, the new fringe width becomes:

β' = β/μ

Given:

β = 2.4 μm

μ = 1.2

Substituting:

β' = 2.4/1.2

β' = 2 μm

The fringe width decreases because light travels with a smaller wavelength inside a medium. Since fringe width is directly proportional to wavelength, the interference fringes become closer together.

This principle is often used in optics experiments to study refractive indices of different materials and verify wave properties of light.

Therefore, the fringe width in the medium is:

2 μm