In a Young's double slit experiment, a combination of two glass wedges A and B, having refractive indices 1.7 and 1.5, respectively, are placed in front of the slits, as shown in the figure. The separation between the slits is = 2 mm and the shortest distance between the slits and the screen is D = 2 m. Thickness of the combination of the wedges is . The value of as shown in the figure is 1 mm. Neglect any refraction effect at the slanted interface of the wedges. Due to the combination of the wedges, the central maximum shifts (in mm) with respect to O by ________. [2025]

(1.2)
From figure,
