In Young's experiment, light of wavelength 6000 is used to produce fringes of width 0.8 mm at a distance of 2.5 m. If the whole experiment is deen in a liquid of refractive index 1.6, then fringe width will be : (1) 0.5 mm (2) 0.6 mm (3)0.4 mm (4)0.2 mm