A double-slit experiment is immersed in a liquid with a refractive index of 1.33. The separation between the slits is 1.0 mm and the distance between the slit and screen is 1.33 m. If slits are illuminated by a parallel beam of light whose wavelength is 6300 Å, then the fringe width will be:

Explanation

When light travels through a medium with a refractive index, its wavelength changes according to the formula λ' = λ / n, where λ' is the new wavelength, λ is the original wavelength, and n is the refractive index. In this case, the new wavelength in the liquid is 6300 Å / 1.33 = 4736.84 Å. Using this adjusted wavelength in the fringe width formula, we get a fringe width of 0.63 mm. Options A and B do not account for the change in wavelength due to the refractive index, leading to incorrect results. Option D is a general 'none of these' choice without providing any calculation.