USAGE

Newton`s Ring Apparatus is one of the basic experiment at graduation level. With the help of this apparatus, the wave nature of light is confirmed. It is based on the phenomenon of interference of light waves obtained from single coherent (of same frequency and constant or zero phase difference).

Newton's Rings, Newton's Rings in Interference

When a plane-convex lens of large focal length is placed as a plane glass plate, A thin film of air is formed between the lower surface of the plate. ... These circles or rings are called Newton Rings

Principal & 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.

Scope of Learning

· Determination of the Wavelength of sodium light by measuring the diameters of Newton's rings

· Determination of the Refractive Index of a liquid transparent medium such as water using Newton's ring apparatus

Compact instrument with full arrangements for conducting Newton's Ring experiment.

FEATURES

MOTION:         A microscope with x-y-z axes movement

BODY                 iron die cast body silver painted,

MICROSCOPE A standard microscope unit with 30x magnification and rotatable cross line eye piece. Focusing of microscope is through Rack and Pinion.

MAGNIFICATION 30x magnification and rotatable cross line eye piece

MOVEMENT :        Longitudinal movement of 26 mm is done by rotating the drum provided which reads up to 0.001cm. Horizontal measurement scale with                                 fine and coarse movement screw I.E loosen the screw and push pull by hand for course motion.

NEWTON 'S RING ASSEMBLY

 A Newton's ring microscope has a built in turning reflector glass plate to reflect a parallel beam of light onto the lens-glass plate assembly. 

Figure 3 shows two types of Newton's ring microscopes

consists of plano-convex lens mounted on an optically plane glass plate, provided with three screws for adjust the so newton's ring formed. 

Adjustable plane glass plate is provided to be inclined at 45 deg  with respect to the vertical plane(a screw provided for rotating it.). 

THIS ASSEMBLY is provided with a Plano-Convex Condensor fixed in metal aluminum diecast Newton's Ring assembly.

NOTE: The optical parts are detachable to identify the lens and glass plate. Both the lens and the glass plates are placed within the lens holder. Then they are covered with a hollow circular cap. The whole assembly is held together in one microscope by using screws