In a Young’s double–slit arrangement, monochromatic light of wavelength 600nm is incident on two narrow slits that are 0.40mm apart. The screen is placed 1.5m from the slits.
(a) Calculate the fringe width on the screen, expressing your answer in millimetres.
(b) If the slit separation is increased to 0.80mm while all other conditions remain unchanged, determine the new fringe width.