Newton's rings

Principle

When a parallel beam of light strikes a tapered film of air created between one plane and one spherical glass body, a pattern of concentric ring-shaped bands is formed due to interference of light waves. The arrangement is called the Newtonian chromatic glass and the interference pattern Newton's Rings.

These interference rings are brought about because a part of the light passes directly through the plane-parallel plate and the lens body and another part is first reflected at the lens surface and then at the glass plate (comp. Fig. ).
The students should become familiar with the phenomenon of Newton's Rings; they should gather measurement data on the phenomenon in an experiment and learn to pull this data to a practical use.

Benefits

• Multifunctional light box - All-in-one: Can be used for geometric optics on the table, colour mixing and on an optical bench
• Extension with others sets at anytime, no additional light sources needed, recognition value for students

Tasks

How can we explain the phenomenon of Newton's Rings? Direct a parallel beam of light through a Newtonian chromatic glass and with the aid of the resulting rings, determine the radius of the lens-shaped glass body.