A double - slit apparatus is immersed in a liquid of refractive index `1.33` it has slit separation of 1mm and distance between the plane of slits and screen `1.33` m the slits are illuminated by a parallel beam of light whose wavelength in air is 800 nm.
(i) Calculate the fringe width.
(ii) One of the slits of apparatus is covered by a thin glass sheet of refractive index `1.53` Find the smallest thickness of the sheet to bring the adjacent minima on the axis.

Explanation

To solve the problem step by step, we will break it down into two parts as stated in the question.

### Part (i): Calculate the Fringe Width

1. **Identify the given values:**
- Refractive index of liquid, \( \mu_L = 1.33 \)
- Slit separation, \( d = 1 \, \text{mm} = 1 \times 10^{-3} \, \text{m} \)
- Distance from slits to screen, \( D = 1.33 \, \text{m} \)
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