Light of wavelength 500nm falls on two slits 0.40mm apart in a typical Young’s arrangement. The screen is at a distance of 1.5m from the slits. Consider the straight line segment on the screen that extends from y1=0.20mm to y2=2.80mm above the central bright fringe.
(i) Determine the total number of complete bright fringes whose centres lie on this segment.
(ii) Determine the total number of complete dark fringes whose centres lie on the same segment.
(iii) If the upper end of the segment is moved further up until the next bright fringe centre just appears completely within it, by how much (in millimetres) must y2 be shifted?