Refraction of light (Question 3 (6 Marks)) — UPSC Physics Optional IFoS 2023 Paper I

In the above experiment, a shift of 100 fringes is obtained when all the gas is removed from the tube. Calculate the refractive index of the gas if the wavelength of light used is 6000\text{ \AA} and the length of the tube is 10\text{ cm}.