A green laser illuminates a double-slit, producing a fringe pattern on a screen ~2 m downstream from the slits, with a spacing of ~2 mm between fringes, with around 30 fringes clearly visible. (a)Estimate, roughly, the width of the slits and the separation between them.(4) (b)A very thin sliver of glass, with thickness ~500 nm, is placed in front of one of the slits. Describe how the fringe pattern changes and estimate, roughly, how large is the change.(4)

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