NEWTON’S RINGS - Q19

19) What do you understand by (a) fringes of equal thickness (b) fringes of equal inclination and (c) fringes of equal chromatic order?

Ans: 

• Fringes of equal thickness: fringes which are separated by equal distances are called fringes of equal thickness.
• Fringes of equal inclination: a pattern of alternating light and dark bands observed when a transparent layer of constant thickness (a plane-parallel plate) is illuminated with a diverging or converging beam of monochromatic light. Each fringe passes through those points of the layer on which the light rays are incident at the same angle φ—hence the term “fringes of equal inclination.”
• Fringes of equal chromatic order: fringes which have same chromatic properties are called fringes of equal chromatic order.