NEWTON'S RINGS APPARATUS

Principle and Working :
A plano-convex lens is placed with its convex surface on the optically plane glass plate so as to enclose a thin film of air of varying thickness between the lens and the plate. Light from an extended monochromatic source is converted into a parallel beam of light by using a convex lens of short focal length and made to fall on an optically plane glass plate inclined at an angle of 45° to the vertical, where it gets reflected on to the Plano-convex lens. The wavelength of monochromatic light source is determined from the radii of the interference rings.

Exp-1 To determine the wavelength of sodium light.
Exp-2 To determine the refractive index of a liquid by using Newton’s rings apparatus.
Exp-3 To find the radius of curvature of planoconvex lens using Newton’s rings experiment, given λ=5893A°.
Exp-4 To find the thickness of a thin sheet of paper (air wedge experiment)..