A double slit interference pattern is produced on a screen, as shown in the figure, using momochromatic light of wavelength 500 nm. Point P is the location of the central bright fringe, that is produced when light waves arrive in phase without any path difference. A choice of the three strips A, B and C of transparent materials with different thickness and refractive indices is available, as shown in the table. These are placed over one or both of the slits, singularly or in conjunction causing the interference pattern to be shifted across the screen from the original pattern. In the Column - I, how the strips have been placed, is mentioned whereas in the Column-II, order of the fringe at point P on the screen that will be produced due to the placement of the strip(s), is shown. Correctly match both the column.

Answer

A-r; B-r; C-s; D-p