When Light is reflected between a spherical surface and an adjacent touching flat surface, an interference pattern is formed. This phenomenon is called Newton’s Rings. The apparatus required to view this interference is called Newton’s Rings Apparatus.
In Newton’s Rings Apparatus, the light from the Condenser lens incidents on the plane glass inclined at 45 degrees and gets reflected vertically downwards and falls on the combination of palno convex lens and plain glass. Some portion of the light is reflected from the lower convex side of the lens and some portion of light is reflected from the upper side of the plain glass plate. A phase difference is created between the two wave fronts that gives rise to dark and bright concentric rings which are viewed through the microscope provided with a high quality Achromatic objective, a Ramsdons eyepiece and a cross line graticule. The diameter of the rings can be measured using the micrometer.
Vashishat Labs Newton Rings Apparatus is compact in design; consists of a heavy metal base with 2 levelling screws. This base carries a 4x4 steel box in which the sodium lamp is suspended from a rectangular metal top.
Specifications
Least count of the micrometer provided is 0.01mm.
Micrometer slide total travel distance is 0-20mm.
Scope of Learning
To determine the
wavelength of sodium light.
To determine the refractive index of a
liquid by using Newton’s rings apparatus.
To find the radius of curvature of
planoconvex lens using Newton’s rings experiment, given =5893A°.
To find the thickness of a thin sheet of
paper (air wedge experiment).