A vessel ABCD of 10 cm width has two small slits s1 and S2 sealed, with identical glass plates of equal thickness. The distance between the slits is 0.8. mm. POQ is the line perpendicular to the plane AB and passing through O, the middle point of S1 and S2. A monochromatic light source is kept al S. 40 cm below P and 2m from the vessel, to illuminate the slits as shown in the figure below. 40cm Calculate the position of the central bright fringe on the other wall CD with respect to the line OQ. Now, a liquid is poured into the vessel and filled up to-OQ. The central bright fringe is found to be at Q. Calculate the refractive index of the liquid

Answer

(a) 2 cm (b) 1.0016