Interference fringes are produced by Young’s method. The
wavelength of light is 6.0 x10-5 cm. When a film of material 3.6 x10-3
cm thick was placed over one of the two slits, the fringe pattern was displaced
by a distance equal to 30 times that between two adjacent fringes. Calculate
the refractive index of the material. To which side are the fringes displaced?
