An important application of interference in thin films is the formation of Newton’s rings. They are observed when light is reflected from a plano-convex lens of a long focal length placed in contact with a plane glass plate. It is named after Isaac Newton, who investigated the effect in his 1704 treatise Opticks. From above, we conclude that the Newton's rings can be explained on the basis of wave theory of : light. The circle AOBE is completed such that OOCE is its diameter. For the m th ring: [(0.14x10-2) 2]/R = mx589x10-9 When a light ray is incident on the upper surface of the lens, it is reflected as well as refracted. The phenomenon of Newton’s rings, named after sir Isaac Newton who first studied them in 1717, Newton’s rings is a pattern of interference caused by two surfaces after reflection of light – a sphere surface and an adjacent flat surface. From 2.22 and 2.23 it is clear Newton's Rings Formula? rings are seen around dark centre later illumination is seen in the field of To set up and observe Newton’s rings. order bright fringe will be, The diameter of bright ring is The bright and dark patterns that appear at the interfaces of two nominally flat pieces of glass are called Fizeau fringes. newton’s rings iv- tau: group i project date client december 2011 physics 3 Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. Where ‘t’ is the thickness of air film. The two beam of reflected light super impose to each other giving rise to interference. If the wavelength of sodium light is 589 nm, calculate the radius of curvature of the lens surface. The occurrence of the Newton’s rings can be explained on the basis of Wave theory of light An air film of varying thickness is formed between the lens and the glass of sheet When a light ray is incident on the upper surface of the lens, it is reflected as well as refracted Newton's rings is a phenomenon in which an interference pattern is created by the reflection of light between two surfaces; a spherical surface and an adjacent touching flat surface. Newton’s rings, in optics, a series of concentric light- and dark-coloured bands observed between two pieces of glass when one is convex and rests on its convex side on another piece having a flat surface.Thus, a layer of air exists between them. R = radius of the lens surface. Newtons Ring. Newton’s Rings Newton’s ring is a process in which Circular bright and dark fringes obtained due to air film enclosed between a Plano-convex lens and a glass plate. Maxima (Bright Fringe): The effective path difference ; substituting this in equation 2.21, Condition for Minima (Dark Fringe): The effective path difference; substituting this in equation 2.21. The perpendicular AM and BN is drawn to glass plate such that AM =BN=t. 1 Answer. near to point of contact  is small; 6 Place a black felt cloth under the Newton's Rings apparatus and position the color CCD video camera and light source on opposite sides of the apparatus to secure an approximate 45° reflection. Find the refractive index of given liquid. When a plano convex lens of long focal length is placed over an optically plane glass plate, a thin air film with varying thickness is enclosed between them. I have compared the measurements of the radius of curvature of my friends measurement, and found that the newtons ring and spherometer measurement deviates upto 3cm. Newton’s rings . To Determine the Wavelength of Sodium Light using Newton’s Rings Sodium Lamp Travelling Microscope P G L Figure 8.1: Apparatus for observing Newton’s rings (8.1) 2t = m‚ (destructive interference or dark rings) where m is the order of the ring and can take the values m = 0, 1, 2, 3::: The Newton’s rings are not equally spaced because the diameter of ring does not increase in the same proportion as the order of ring and rings get closer and closer as ‘n’ increases. R2 = ( R − t) 2 + r2 which gives. Experiment8. The diameter of nth An air film of varying thickness is formed between the lens and the glass sheet. plural noun Optics. Newton's Rings Circular interference formed between a lens and a glass plate with which the lens is in contact. One newton is the force needed to accelerate one kilogram of mass at the rate of one metre per second squared in the direction of the applied force. 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