Newton’s Rings Experiment Viva Questions and Answers 2023

The path difference along the circle is constant that’s why the rings are circular in this Newton’s rings experiment.

In Newton’s rings arrangement, the locus of point of equal thickness of air film lie on a circle with the point of contact of the plano-convex lens and the glass plate as centre. Therefore the fringes are circular and concentric.

In the case of wedge shaped air film, the loci of points of equal thickness are straight lines parallel to the edge of the wedge so the fringes are straight and parallel.

The basic principle of Newton’s rings experiment is interference phenomenon.

The phenomenon of redistribution of light energy in a medium on account of superimposition of light waves from two coherent source is called interference of light

                                          OR

The phenomenon of Newton’s rings is an illustration of the interference of light waves reflected from the opposite surface of a thin film of variable thickness.

Two sources are said to be coherent if they emit continuous light waves of the same frequency or wavelength, nearly of the same amplitude which have either in phase or have constant phase difference.

Alternate dark and bright rings with central dark spot are called Newton’s rings.

For interference

When two light waves interfere at each other such that the resultant intensity at a point increase due to the interference of two waves is called constructive interference.

If the resultant intensity is minimum then that is called destructive interference.

For normal incidence of light wave.

Because the plano Convex lens and the plano lens both are in contact and at that particular place the centre dark ring will appear.

Monochromatic light. Example : Sodium light

Coloured fringes will form.

No, because both are monochromatic lights only.

If the entire arrangement is dipped into water then the diameter of rings decreases.

Fringes disappear