A double-slit system with separation 0.20mm is illuminated by light of wavelength 589nm in air. The screen is 1.6m away.
(i) Calculate the fringe width in air.
(ii) The entire apparatus is now immersed in kerosene of refractive index 1.44. Assuming the slits themselves are in the kerosene, determine the new fringe width observed on the screen.
(iii) Keeping the kerosene bath, the experimenter wishes to restore the original fringe width by moving the screen. By what distance and in which direction must the screen be moved?