MHTCET 14 May 2023 Shift 2 Solved Paper

On replacing a thin film of mica of thickness 12×10−5‌cm in the path of one of the interfering beams in Young's double slit experiment using monochromatic light, the fringe pattern shifts through a distance equal to the width of bright fringe. If λ=6×10−5‌cm, the refractive index of mica is