Subject: Applied Physics 2

Topic: Interference And Diffraction Of Light

Difficulty: Medium

In both air-wedge film and Newton’s ring experiments, each fringe is the locus of points of equal thickness of the film. In Newton’s rings arrangement, the locus of points of equal thickness of air film lie on a circle with the point of contact of plano-convex lens and the glass plate as center. So, the fringes are circular in nature and concentric.

For wedge shape air film, the locus of points of equal thickness are straight lines parallel to the edge of the wedge. So, fringes appear straight and parallel.