An interference pattern with Young's double slits 1.5mm apart is formed on a screen at a distance 1.5m from the plane of the slits. In the path of the beam from one slit, a transparent film of thickness 10μm and refractive index 1.6 is interposed. In the path of the beam from the other slit, a transparent film of thickness 15μm and refractive index 1.2 is interposed. Find the displacement of the fringe pattern.