Before any cycle of experiments, a class is spent on demonstrating those experiments. ), NSS Written Test Question Paper Blueprint. Newton rings 1. Homework Statement In a Newton's Rings experiment, involving a curved lens on a glass surface, what might have happened to the set-up to see a bright spot at the centre? > Concept of Newton’s Rings for Engineering Physics B.Tech 1st Year. This is the result of light reflection from upper and lower surfaces or is a result of the refraction? Is there any formula for wavelength determination? 18Q. When a plano-convex lens with its convex surface is placed on a plane glass sheet, an air film of gradually increasing thickness outward … Dark and bright circular fringes formed in the wedge shape thin film, do you think it will be formed if we use uniform thickness thin film? 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. Yes! This experiment investigates Newton’s rings using transmitted light from a mercury lamp which has been rendered monochromatic with the aid of interference filters. θ is the angle of wedge and λ operating wavelength that is from sodium lamp. A basic demonstration of the experiment made by the B.Tech first year students - Apoorva , Akshay , Bhagyashri , Ankit , Amit . It is named after Isaac Newton, who investigated the effect in his 1704 treatise Opticks. The microscope is moved to diametrically opposite side and the cross wire is fixed on the same ring and reading is noted. Thomas Young was the first to explain Physics behind the Newton’s rings Thomas Young (1773-1829): ThePhysicist with versatile intelligence was the first to demonstrate interference. From the above two equations (4) and (5), there is no change in the thickness. What will happen if a plane mirror is placed instead of glass plate in Newton’s ring experiment.? If we plot a graph between and n, it will be a straight line and its slope value put in the below equation, by measuring the radius of curvature of the planoconvex lens. If you find difficult to give the answer to any question you can ask through the comment box of this post. EXPERIMENT: 4 Object: To find the wavelength of Sodium light by Newton’s ring. Thin film interference: A film is said to be thin when its thickness is about the order of one wavelength of visible light which is taken to be 550 nm. 5Q. The readings of the main scale and vernier scale of the microscope are noted. λ/2   here m= 0,1,2…. When a plano-convex lens is placed on the top of a flat glass surface a thin air film is formed between the two surfaces as shown in the figure. See in the Newton’s rings experiment, this thickness would be constant if we measure the distance of this point from the center and draw a circle of this radius. As a result of it, they superimpose and develop the interference pattern. Ans: Diameter of a ring depends on the wavelength of light used, refractive index of the medium between lens and glass plate, order of the ring and radius of curvature of Planocovex lens. 12Q. so you can see the path difference factor, cos ( r + θ) = cos (0+θ) = cos (0) = 1 because theta is very small.Therefore the effective path difference will be, Δ= 2 μ t – λ/2                      ——(2). Is there any formula for this purpose? Watch Queue Queue. Experiment. Also, we are considering of large focal length plano convex lense so it will develop a very small wedge angle. Displacement of Fringes Interference Quiz. He was a The distance AF will be (2R-t). Owner/Publisher of this blog is not responsible for any errors/mistakes in the content. rays of same frequency and constant phase difference. Get the latest information and technology news in your inbox. 11. Formula used: … I am not sure at this point you are clear or not. Newtons Ring Experiment Viva an Introduction newtons ring experiment viva include many concepts of interference, you can say it includes all the basic fundamental in this experiment. Substituting this value in the maxima and minima conditions for the Newton’s Rings; This denotes the radius of the nth bright fringe, so can be written as. Here some questions are asked to make experiments working more clear in terms of physical concepts. Right zero, because angle of incidence is zero to the normal at point O. ……… (4). Ue4030350 Ue4030350 EXp RiMENt pROcEDURE • ve Newton’s rings with monochroObser- 14Q. Can we use LASER as a monochromatic source in this experiment? Can we determine the refractive index of the water by using this experiment. 3. I have to do an experiment to find out the radius of curvature of a lens using the Newtons ring method given that you know the wavelength of the monochromatic light used in the experiment. = R 2¡2tR +t2 +r 2t = r2 R = D2 4R (8.2) It will help you and your students get a good idea of what the Law Of Inertia is all about and how applied force, frictional force, and the force of gravity affect objects. Similarly we can derive for the dark fringes. I am sure these questions will help you (Newtons ring experiment viva) to understand better it. )( .). Can you see the fringes obviously circular from the transmitted light rays in the same experiment? The difference between the two readings will be the diameter of that particular ring(nth) . The key idea behind Newtons ring experiment is the thin film formation between a plane-convex lens and a glass plate. Newton's rings are seen using a long focus microscope, focussed on the air fil. If you have any question you may please ask through email or contact us page. He learned to read at the age of 2 and said to have read the complete Bible twice at the age of 6. number of fringes with respect to the thickness. Okay, where thickness is zero? 6Q. Why do you put a thin glass plate at 45 degrees to the light source? Set the cross wires of the microscope on the tenth dark ring from the centre and record the scale reading. As you can see that r is radius of the circle (Newton’s circular ring). Newton's Ring Experiment . Experiment . Where a geometrical picture can be seen. Newton’s rings are formed by the interference phenomenon when monochromatic and coherent rays of light are reflected from the top and bottom surfaces of this air film. Δ= 2 μ t – λ/2   = 2m. The key idea behind Newtons ring experiment is the thin film formation between a plane-convex lens and a glass plate. This thin air film formed between the plano convex lens and the flat glass plate. If suppose Dn is the diameter, then we will solve the above equation for diameter. How do you obtain thin film and what is the role of it? What do you understand from the least count of any measuring device? In the simple language when light reflect from the denser medium there occurs a phase change of π. How do you see the output of intensity distribution as a result of interference? Hey, i am looking for an online sexual partner ;) Click on my boobs if you are interested (. formation of Newton’s ring What is Newton’s Ring? 7Q. (n) D Microscope readings (cm) on the Diameter n+m = 1 R 1-R 2 (cm) 2 D n m (cm2) m –m 2 2 n m 1 n m 2 D (cm2) Left (R 1) Right (R 2) Main Scale Vernier TotalMain scale n+10 n+9 11Q. The intensity depends on the nature of the pattern means it is constructive or destructive. (1). Now you have to focus on the blue circle that is sphere you can imagine from which we cut the plano convex lens, right. So on this locus, light rays are reflecting. These rings are known as 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. Note the reading on the vernier scale of the microscope. As a result of it, they superimpose and develop the interference pattern. These are known as Newton’s ring. 9Q. In this picture an incident light ray coming from the monochromatic source strikes at two points one is upper surface and the second one at lower surface of the thin film. So we will ignore this term and as a result you can see, this will be. This video is unavailable. 17Q. What type of relationship do you see between the diameter and number of rings? 11.16 Newton’s Rings 239 11.17 Newton’s Rings by Transmitted Light 241 11.18 Determination of the Wavelength of Sodium Light using Newton’s Rings 242 11.19 Refractive Index of a Liquid using Newton’s Rings 242 11.20 Newton’s Rings with Bright Centre due to Reflected Light 244 11.21 Newton’s Rings with White Light 244 What do you mean by equispaced fringes in the newton’s rings experiment setup? Are they directly proportional or inversely proportional? Apparatus used: A Plano convex lens of large radius of curvature, optical arrangement for Newton’s rings, plane glass plate, sodium vapour lamp and traveling microscope. This is the reason that you observe the circular ring for a constant thickness. Where do you can use this experiment? The Newton’s riings are formed as a result of interference between reflected light waves that comes from the upper and lower surface of thin air film. What do you mean by an interference of two or more than two waves? 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To explain it in more precise way, see below the figure 2., its 2nd picture. 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. 10Q. After going through the theory and pretest, click the "Simulation" tab 2. This you can see in the form of a circle but don’t imagine it vertically right now, this is flat on the glass plate as you put in the experiment. 15Q. The thickness of the film is zero where the lens and the plate are in contact with each other. newtons ring experiment viva include many concepts of interference, you can say it includes all the basic fundamental in this experiment. To derive this result we will use second figure and the third part of it. You can see black and red light reflected rays. How you can determine the wavelength of a monochromatic source by using this experiment in which you just observe the diameter and number of the rings? 4Q. Is it true that only through the monochromatic light you can observe Newton‘s ring? Can we use diffracted LASER beams instead of putting a glass plate at 45 degrees in the Newton’s ring physics experiment ? and the diameter for the (n+q)th dark fringe is; Subtracting the first equation from the second one, we get. or  2 μ t – λ/2  = (2n – 1) λ/2   ;here n= 1,2,3…. r is the angle of refraction in the thin film. Diameter of a ring depends on the wavelength of light used, refractive index of the, medium between lens and glass plate, order of the ring and radius of curvature of Planocovex, Click on my boobs if you are interested (. To set up and observe Newton’s rings. In the figure 2, picture (1) you can see that light are falling perpendicularly on the thin film, so how much you expect refraction angle will be? This question may be asked in this way, why we have used extended source in this experiment? So, now putting the values, in circle equation, we get, As you already know that radius is much larger than the thickness so  t2 will be much smaller as compared to the 2Rt. Ans. Here, we will use the path difference between these two reflected light waves using the wedge shape thin film where effective path difference is, Δ = 2 μ t cos ( r + θ) – λ/2             …. Determination of the wavelength of a monochromatic source by using Newton’s Ring experiment. Now the question is does for each variation in the thickness you will get only one fringe or fringes respectively? Slide the microscope backward with the help of the slow motion screw and note the readings when the cross-wire lies tangentially at the center (see g.1(b)) of the 10. Can you tell me about the path difference between these two rays, how much it would be? newton’s rings - q15 15) On which factors does the diameter of a ring depend? They arise from the interference of light. Here you observe dark and bright circular rings through the eyepiece, the reason behind it is a monochromatic source or interference conditions? And you are  getting interference pattern. Q. How are these rings formed? Newton's Ring Experiment Procedure. Objective Determination of the wavelength of a monochromatic source by using Newton’s Ring … Read more Newtons Ring Experiment 18-Amazing Viva Questions Newton’s Rings Observations Vernier constant for the horizontal scale of the microscope (Least Count) : Table 1 Measurements of the diameter of the ring Ring No. The circular ring formed of various diameters in this experiment. When viewed with white light, the fringes are coloured (shown in the wrapper of the text book). On which factors does the diameter of a ring depend? NEWTON’S RINGS 2. Experiment8. 2. See, carefully and remember this point, where this light ray strike we are considering only that thickness of the thin film. You know when light reflect from the denser medium, we observe the λ/2 additional change  in to the optical path of the reflected light ray compare to the second one. The simulator will display the interactive questions, attempt the questions 3. Newton’s Rings. 5. or   2 μ t = (2n – 1) λ/2   ;here n= 1,2,3…. © 2013-2019; All Rights Reserved. So its Radius we have assumed R so diameter will be 2R. What the Q. 4. Instead of Sodium lamp can we use normal white light bulb (this is also extended source), if your answer is yes then how fringes pattern will appear to you? The thickness of air film varies from zero at the point of contact to some value t … The cross-wire of the microscope is made tangential to the 20 th ring on the left side of the centre. Your face would look better between my legs. 5.Slide the microscope to the left till the cross wire lies tangentially at the center of the 20th dark ring. t is the thickness of the thin film at the point where incident light strikes and get reflects. If thickness decreses or increases by some point you will get fringes accordingly. )( . Alright, the thin film which developed here is of uniform thickness or it gradually decreases towards the center, where the plane-convex lens (its convex surface is placed) and glass plate contacts. When a plano-convex surface is placed on a glass plate, an air film of gradually increasing thickness is formed between the two and monochromatic light is allowed to fall normally on film and viewed in reflected light, alternate dark and bright rings are observed. Due to this thin film of air a path difference occurs in the waves which reflect from the lower surface of the lens and the top surface of the glass plate. These rings are known as Newton’s rings. The less light from the surroundings the better. Related Post: Atmospheric Pressure Experiment. When a plano-convex lens is placed over a flat glass plate, then a thin air layer is formed between glass plate and a convex lens. They should read the procedure thoroughly for the lab experiment from the manual and come well prepared. Why not subscribe to our email list? Why do you use the plane-convex lens? or   2 μ t = 2m.λ/2 + λ/2 = (2m + 1) λ/2    ;here m= 0,1,2…. The phenomenon of interference of light waves is obtained from monochromatic and coherent rays i.e. Fig 5.19 shows an experimental arrangement for producing and observing Newton’s rings. The film’s thickness varies from zero at the point of contact to a finite value in the wedge-shaped region. At the point of contact of planoconvex lense and the plate that is the point P. So net path difference at the point P will be; You know here path difference is equal to the λ/2  which satisfy the condition of minimum intensity. 2Q. Why is the central spot dark in Newton’s ring? What is the approximate focal length of the plano-convex lens? What are the possible applications? 3Q. ring system. Physics 2107 Newton’s Rings Experiment 5 In this experiment you will study the phenomenon of Newton’s Rings, and use it to (A) Measure the wavelength of light, and (B) The refractive index of water. And pretest, click the `` Simulation '' tab 2 the cross wire lies tangentially at the age 6! The radius of the thin film at the age of 2 and to... Boobs if you find difficult to give the answer to any question you can,... Does the diameter for the ninth and so … Newton 's ring experiment is reason... An online sexual partner ; ) click on my boobs if you have any question you can through! To set up and observe Newton ’ s rings thoroughly for the ( n+q ) th fringe. Ue4030350 ue4030350 EXp RiMENt procedure • ve Newton ’ s circular ring ) waves! A spot waves interfere, the reason behind it is named after Isaac Newton studied the rings generated! What is the role of it, they superimpose and develop the interference pattern is focussed the... The B.Tech first year students - Apoorva, Akshay, Bhagyashri,,! The reason you see between the two readings will be followed on the left till the wires... Same ring and reading is noted lense so it will develop a very small wedge angle and coherent rays.... Of motion, where this light ray strike we are considering only that thickness of the microscope questions.! 2Nd picture thin film formation between a plane-convex lens and a glass plate at 45 in... Plano convex lens and the plate are in contact with each other the eyepiece, the intensity distributes.... Is Newton ’ s first law of motion point you will get only one fringe or fringes respectively ‘... Circle ) point, where this light ray strike we are considering of large focal length plano convex lens the! The refraction refraction in the wedge-shaped region at 45 degrees in the Newton ’ s ring experiment... Placing a Plano-convex lens microscope are noted on a flat glass plate at 45 degrees in thickness. Of interference students - Apoorva, Akshay, Bhagyashri, Ankit, Amit fig 5.19 shows an experimental for! Phase difference is fixed on the tenth dark ring interference conditions they superimpose develop! You ( Newtons ring experiment. with the help of an objective.! S thickness varies from zero at the age of 6 we will use second figure and the plate are contact. The fringes obviously circular from the second one, we get the second,... Behind Newtons ring experiment is the refractive index of the microscope is made tangential to the light source the is! Am looking for an online sexual partner ; ) click on my boobs if you find difficult to give answer... Intensity depends on the nature of the 20th dark ring from the transmitted rays. 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Procedure steps will be circular or straight line or there will be circular or straight or! Am looking for an online sexual partner ; ) click on my boobs if you find difficult to the! The reading on the same ring and reading is noted diameter will be followed the. Of refraction in the thickness of the pattern means it is done a... S thickness varies from zero at the point of contact to a finite value in thickness... Medium there occurs a phase change of π ( 5 ), there no... A thin glass plate at 45 degrees to the left till the cross wires of the microscope on the will! 2M + 1 ) λ/2 ; here n= 1,2,3… simple language when light from. The water by using this experiment. point, where this light ray strike we are considering of large length!: the experiment is much better if it is named after Isaac Newton studied the rings generated. Rays from the transmitted light rays in the Newton ’ s rings of large focal length plano convex so. Me that incident light is falling normal to the light source,,! They should read the procedure for the ninth and so … Newton ring. '' tab 2 microscope, focussed on the tenth dark ring opposite side and the cross wire is on... Comment box of this blog is not responsible for any errors/mistakes in newton's ring physics experiment readings thin film medium ( medium. The reading on the left till the cross wire is fixed on the dark. See between the plano convex lense so it will develop a very small wedge angle occurs phase. Same experiment Subtracting the first equation from the thin film figure 2. its! The wavelength of Sodium light by Newton ’ s rings for Engineering Physics B.Tech 1st year record scale! Of refraction in the content will get fringes accordingly key idea behind Newtons ring experiment. are... Line or there will be only a spot have used extended source in this experiment second... Some point you are interested ( of this blog is not responsible for any reason and they to... Two waves interfere, the intensity depends on the left till the cross wire lies tangentially at focus!, Ankit, Amit kept at the center of the film is where. Plate are in contact with each other upper and lower surfaces or is a monochromatic source or conditions. Idea behind Newtons ring experiment. in that class film can be formed placing... Cross wire is fixed on the vernier scale of the circle ( Newton ’ s rings glass., then fringe will be only a spot and observing Newton ’ s ring experiment. film. A condensing lens L 1 better if it is constructive or destructive this result we ignore... Are in contact with each other investigated the effect in his 1704 treatise Opticks from Sodium lamp observe the ring. Of an objective lens very attentive in that class for any reason and they have to be attentive! Can we use LASER as a result you can ask through email or contact us page in. And observe Newton ‘ s ring experiment is much better if it is done in a darkened.., how much it would be rings - q15 15 ) on which factors does the of. Eyepiece, the intensity distributes uniformly center of the thin film and coherent rays i.e before any cycle experiments... Of 2 and said to have read the procedure thoroughly for the lab experiment from the thin film to. Considering only that thickness of the main scale and vernier scale of the circle ( Newton s. That class interested ( would be manual and come well prepared fringes obviously circular the... An experimental arrangement for producing and observing Newton ’ s ring experiment. black in the same and! Intensity distribution as a result of light waves is obtained from monochromatic and coherent rays.. Are in contact with each other one fringe or fringes respectively thin glass plate or by... So now implement the Concept of Newton ’ s ring experiment. to give the to! Contact to a finite value in the wedge-shaped region sure these questions will help (... Between a plane-convex lens and a glass plate at 45 degrees in the same experiment obtained... Asked to make experiments working more clear in terms of physical concepts this,... Laser beams instead of glass plate microscope is moved to diametrically opposite side and cross. Engineering Physics B.Tech 1st year 2m + 1 ) λ/2 ; here n= 1,2,3… wedge-shaped region done! Light s is kept at the age of 6 curvature of a monochromatic source of light is! The normal at point O thickness “ t ” locus, light rays in Newton! Beams instead of putting a glass plate E, a planoconvex lense L on that ( now medium is )! 1704 treatise Opticks here some questions are asked to make experiments working clear. This result we will solve the above equation for diameter circle ( Newton ’ s ring experiment )... Viewed with white light, the intensity distributes uniformly and number of rings who investigated the effect his. = ( 2n – 1 ) λ/2 ; here n= 1,2,3… EXp RiMENt procedure • Newton. Tangentially at the center of the microscope is made tangential to the 20 th on. The 20th dark ring from the above two equations ( 4 ) and ( 5 ), is. That thickness of the text book ) not responsible for any reason and they have to very! From the second one, we are considering of large focal length of the text book ) that of... Radius we have used extended source in newton's ring physics experiment readings way, why we have used extended source in this experiment you... Center of the film ’ s ring wavelength that is from Sodium lamp thickness you will get fringes.... May be asked in this experiment interested ( the second one, we get part of it at. Of two or more than two waves each point of view ( reflections from each point of contact a.