0000009658 00000 n d. Now place the spherometer on a flat surface. 0000036813 00000 n Newton’s Rings and Determination of the Wavelength of Light Newton’s Rings. 8. For an air film (µ = 1) between the lens and the glass plate. Change ). The dark and light fringes which are of ring shaped are produced by the air film existing between a plano-convex lens and a plane glass. endstream endobj 51 0 obj<> endobj 52 0 obj<> endobj 53 0 obj<>/Font<>/ProcSet[/PDF/Text]/ExtGState<>>> endobj 54 0 obj[/ICCBased 77 0 R] endobj 55 0 obj<> endobj 56 0 obj<>stream Let, the ray now strikes the upper surface of the air film nearly along the normal. newtons ring Arbor Scientific. 0000010063 00000 n After measuring all the three sides take the mean of all the three sides. Components: Place the lens L at a distance equal to its focal length from the sodium lamp to get a parallel beam of light. 4. At the point of contact ‘O’ as shown in figure 5 , the thickness of the air film is nearly zero and it slightly increases as we move towards the corner of the lens. Find the difference of the values observed for the same left and the right ring . Now again do the same for the same set of dark ring. A system of bright and dark concentric circular rings are observed through a microscope, arranged vertically above the … A Spherometer consists of a linear scale, a circular scale marked on a circular disc at the top, three legs which form the vertices of an equilateral triangle and a middle leg which is movable. When crest of the first wave falls on the crest of second wave and trough of the first wave falls on the trough of the second wave and then the resultant wave is the vector sum of the amplitude of the two superimposing waves which is equal to sum of the amplitude of two waves, this is known as Constructive Interference. 9. The superimposing waves can have constructive or destructive interference. first with a spherical surface and second with an adjacent flat surface) interference pattern is created. 0000009529 00000 n 0000037240 00000 n Newtons Ring Experiment Apparatus Setup Physics Lab. 0000098270 00000 n EXPERIMENT 8 To Determine the Wavelength of Sodium Light using Newton’s Rings Please read additional instructions on the bench for setting up the PC and camera for this experiment Introduction Newton’s rings are interference fringes of equal thickness which are produced in the air film be-tween a convex surface and an optical flat. constructive interference between the light rays reflected from both surfaces. Record the observed values in a table. EXPERIMENT: 1 Object: To find the wavelength of Sodium light by Newton's ring. Two salient reasons: 1. 6.1. which is equal to the difference in amplitude of two waves, . Fill in your details below or click an icon to log in: You are commenting using your WordPress.com account. Aim To determine wavelength of sodium light using Newton’s Rings. where l is the distance between the two legs of the spherometer and h is the height or the thickness of the lens at the center . Aim: To determine the wavelength of sodium light by Newton’s Ring method. Formula used: The wavelength of light is … But this pattern is called as Newton’s Ring because he was the first scientist to observe and explain the phenomenon. The ray is partly refracted in the air film and also partly reflected at the lower surface of the film. APPARATUS A Plane-convex lens of large radius of curvature, traveling microscope, optical arrangement for Newton’s rings, sodium lamp and a spherometer . A beam of monochromatic light emitted from the source ‘S’ and moving towards the lens ‘L’ and then it is reflected from the lens ‘L’ to a sheet of glass ‘G’. Newton's rings are... | Find, read and cite all the research you need on ResearchGate Article PDF Available Analytical Study of Newtons's Rings Concept to Determine the Wavelength of Sodium Light By employing sodium light whose mean wavelength is 5893Å, R can be determined from Eqn. e. The final reading is then calculated using the formula, FR = main scale reading + (circular scale reading*least count), f. Height or thickness of the surface is the difference of final reading and the initial reading, g. Radius of curvature can be calculated using the formula. 0000001634 00000 n EXPERIMENT: 4 Object: To find the wavelength of Sodium light by Newton’s ring. A Spherometer is an instrument used to measure the radius of a spherical surfaces. Using any of the two relations, we can find the wavelength of the monochromatic light used. Light, interference, thin films. Newton’s Ring is the demonstration of the interference of light waves reflected from the surface of a thin air film formed between the plane glass and the convex lens whose thickness varies while moving from the center towards the end as shown in fig 1 . Then the slope of the straight line , tan(ϕ)  will give the wavelength as, Here R is the radius of curvature of the lens that can be found with a spherometer using the relation. The wavelength of sodium light has been determined . Log in. Plot the graph between the no. <<70CD27F00776CD4CB06B8908FFBE6154>]>> optics Radius of curvature of lens Newtons Ring method. Move the cross wire towards left and set it tangentially at the corner of the (n+m), 9. 1 Presented by- Group 1 EE Batch 1 2. c. The initial reading is then calculated using the formula, IR = main scale reading + (circular scale reading*least count). 0000001813 00000 n could you please give the values as well?? first with a spherical surface and second with an adjacent flat surface) interference pattern is created. Enter your email address to follow this blog and receive notifications of new posts by email. These viva questions will help you in your experiment to understand it better. 0000017738 00000 n 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. Pitch of the spherometer can be determined by rotating the circular scale and checking the distance covered by it on the main scale in one rotation. Fig 2:      Robert Hooke                                                                                                                  Issac Newton. When two or more waves having same source and same frequency (coherent waves) interact with each other, then the resulting phenomenon is known as Interference . The key idea behind Newtons ring experiment is the thin film formation between a plane-convex lens and a glass plate. Studying the interference phenomenon due to multiple reflections of light waves from gradually varying air film. If the waves that enter the lens are of arbitrary phase, and of all possible wavelengths Newton's rings in transmitted and reflected white light . 0000019274 00000 n 3. newton s rings experiment theory study material. 3. of rings ‘n’ along the x-axis and the square of the diameter D, http://en.wikipedia.org/wiki/Interference_(wave_propagation), http://en.wikipedia.org/wiki/Newton’s_rings, http://www.physicsclassroom.com/physics-tutorial/interference-of-waves, http://physical-optics.blogspot.in/2011/06/newtons-rings.html. Viva Voce for by Newton’s Ring Q. an application of newton s rings experiment. To find the radius of curvature of the convex lens. The modification in the distribution of intensity in the region of superposition 0000120060 00000 n List of all Other Experiments. on the crest of second wave and trough of the first wave fall, sum of the amplitude of the two superimposing waves. These concentric rings are known as “Newton’s Rings”.Let us consider the figure in which a convex lens of radius of curvature R placed on flat glass plate and it is exposed to monochromatic light of wavelength λ normally. According to geometrical theorem, the product of intercepts of intersecting chord is equal to the product of sections of diameter then. When the two or more waves superimpose over each other, resultant intensity is modified. where θ is the angle of refraction in the air film. Again rotate the middle leg till it just touches the flat surface and note the main scale and circular scale reading. 0000016128 00000 n 5. 0000013889 00000 n The ray reflected from F suffers an additional phase change of π  or a further increase in the path difference by λ/2 . at the point of contact between the lens and the glass surface. 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. 0000112756 00000 n View Newton's ring.pdf from MATH 111 at Pandit Deendayal Petroleum University. Let, the ray now strikes the upper surface of the air film nearly along the normal. 0000010642 00000 n Newton s Rings Apparatus indosawedu com. 6. 7. Plot the graph between the no. A branch of physics concerned with the study of light, its production, propagation, measurement and properties. 0000001989 00000 n 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. Adjust the microscope vertically above the center of the lens. Issac Newton in 1717, first observed an interference pattern formed by the reflection of light between a spherical surface and an adjacent flat surface. Measurement of Wavelength of Sodium Light By Newton’s Rings. 0000010347 00000 n to … In this apparatus, light from a sodium lamp falls on the glass plate, inclined at 45 degree to the horizontal, get reflected, and then falls normally on the convex lens placed over the glass plate. In transmitted light the ring system is exactly complementary to the reflected ring system so that the centre spot is bright. The first few rings are usually not clear so slide the microscope to the left or right and set it. 0000004407 00000 n 5. 0000048123 00000 n 0000001176 00000 n ( Log Out /  0000002023 00000 n 0000119831 00000 n b. Rotate the middle leg till it just touches the spherical surface and note the linear scale and circular scale reading. of fringes) along x-axis and D2n on y-axis. These rings are known as Newton’s rings. The light which is reflected upwards if seen through the microscope M which is focused on the glass plate, it is observed that the series of dark and bright rings are seen with each of them centered at O. Since the rays are incident normally, θ is zero and hence Cos(θ) =1 . 0000001554 00000 n The simulation virtualizes the Newton’s rings experiment. The user can view the effect of Newton’s rings formed when the medium changes. Different ring pattern can be seen by changing the radius of curvature of the lens and wavelength of light source.. In this experiment, we have taken sodium lamp as the monochromatic source. to determine wavelength of sodium light using newton’s. 0000011596 00000 n 0000023490 00000 n Introduction Newton's Ring is the demonstration of the interference of light waves reflected from the surface of a thin air film formed between the plane glass and the convex lens whose… Place the spherometer on the surface . A convex lens of large focal length is placed in contact of a plane glass plate resulting in the enclosure of the thin air film between the glass plate and the lens. To measure the radius of curvature of a spherical surface : a. Theory: 1-Newtons Rings Date: OBJECTIVE: To determine the wavelength of sodium vapor light by measuring the diameter of Newton’s ring. 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. Click here to get an answer to your question ️ Wavelength of sodium light in newtons rings experiment Now, take out the convex lens and the plane glass out from the case carefully and measure the radius of curvature of the convex lens and also the height of the convex lens with the help of the spherometer. Talk Newton s rings Wikipedia. Fig 1 : placement of plano-convex lens over a plane glass. Create a free website or blog at WordPress.com. Apparatus Required : A plano-convex lens of large radius of curvature, optical arrangement for Newton’s rings, plane glass plate, sodium lamp and travelling microscope. Apparatus Required Newton's rings apparatus, travelling microscope, sodium lamp, a convex lens and a spherometer. If we take a white light then there we observe different colours at the center of the rings so that it is impossible to count the rings that is the reason we do not use white light.. Why we take diameters of two fringes to find out the wavelength of monochromatic light? Note the main scale and circular scale readings present on the microscope in both the cases. 1. startxref A monochromatic source of light S is kept at the focus of a condensing lens L 1. When two or more waves having same source and same frequency (coherent waves) interact with each other, then the resulting phenomenon is known as Interference . Repeat the procedure no. ( Log Out /  Newtons ring experiment viva questions are listed here. If the radius of curvature of the lens is 100 cm, find the wave length of the light. xref Email address: Leave this field empty if you're human: * You will receive the latest news and updates on your favorite celebrities! O. Search. Subscribe Now. wavelength of sodium light using Newton’s. Newton rings are Alternate dark and bright rings formed due to the presence of air film when the plano-convex lens is placed on the glass plate is called newtons rings. was so helpful,,,exact,precise &excellent, why don’t we take a white light instead of monochromatic source, bcz white light made up 7 light it give a coloured rings. 9. Or 0000067576 00000 n Since the rays are incident normally, θ is zero and hence Cos(θ) =1, An alternative and better method is to plot n (the no. Figure 2 The thickness of air film varies from zero at the point of contact to some value t at point P. The reflected rays which are produced at the upper and lower surface of the film, are coherent and interfere constructively or destructively. 7. 2. Pitch is the linear progress made by the circular scale on the main scale in one complete rotation. The wavelength of monochromatic light can be determined as, . Why are Newton s rings circular in shape Why not square. 0000009102 00000 n 0 The superimposing waves can have constructive or destructive interference. A convex lens of large focal length is placed in contact of a plane glass plate resulting in the enclosure of the thin air film between the glass plate and the lens. x�b```g``y����w�A��bl,v�t��������0m�p^e��b����~}:��NǓ.�{ǹ"o(|7(�Y�m�*�����\1e��Ē;�A�ţ���@��84��]\\BCӠ���@��yV��b��?��ʹP�I��UC��������(�03�+�'�ja��}ISw���P��\�S�����c�W{���0��S��#�1�o�#˯pY1��j`e�D�[���7��@l Ć�w�iF ~` �`X� 0000048569 00000 n Ans. Newton's ring experiment 1. 0000120244 00000 n 0000006640 00000 n Newton’s rings apparatus or (two glass plates and a retort stand, boss and clamp) Sodium discharge lamp . Select any one type of medium. where S1, S2 and S3 is the three measured sides of the triangle formed. newton s rings dan macisaac. 50 44 Change ), You are commenting using your Twitter account. it is exposed to monochromatic light of wavelength λ normally. onvex lens of radius of curvature R placed on flat glass plate. Record the observed values . Experiment no. APPARATUS: A Traveling microscope, a sodium vapor lamp, Newton’s rings apparatus consisting of an optically plane glass plate and a convex lens of large focal length placed in a box having an 0000000016 00000 n 1. PY2107 Newton’s Rings Experiment 5 _____ 2.2 To see how Newton’s Rings can be used to measure the wavelength of light, consider the geometry of Fig 2 (although the figure shown is that for a plano-convex lens, it is equally appropriate to our experiment). 2. Least count is the least possible measurement that can be taken with the help of an instrument. of fringes) along x-axis and D, 4. Isaac Newton was the to first study the Newton’s ring pattern in 1717, so it was named as Newton’s rings. Newton’s Ring is the phenomenon in which because of the reflection of light with the two surfaces, (i.e. %PDF-1.4 %���� A beam of monochromatic light emitted from the source ‘, ’ and moving towards the lens ‘L’ and then. For the points D and E to lie on a bright fringe. Physics with animations and video film clips. 0000002099 00000 n DIAGRAM FORMULA The mean wavelength of D1 and D2 lines of sodium light is given by the formula: Take the mean of the two differences calculated . The redistribution of light by superposition of light waves is called as interference. To determine wavelength of sodium light using Newton’s Rings. which is equal to sum of the amplitude of two waves, on the trough of second wave and trough of the first wave is fall. trailer When crest of the first wave falls on the trough of second wave and trough of the first wave is falls on the crest of the second wave and the resultant wave is the vector sum of the amplitude of the two superimposing waves which is equal to the difference in amplitude of two waves, this is known as Destructive Interference. 6. 0000099289 00000 n 0000037059 00000 n When viewed with white light, the fringes are coloured (shown in the wrapper of the text book). Least count is the resultant of the pitch calculated divided by the total no. Because of the constructive interference between the light rays reflected from both surfaces, light rings are formed while the dark rings are formed because of the destructive interference. Apparatus: Traveling microscope, sodium vapour lamp, plano-convex lens, plane … Under white light we get coloured fringes. According to the principle of superposition of waves – When two or more waves of same type are incident at the same point then the total displacement at that point is equal to the vector sum of the displacements of the individual waves. Change ), You are commenting using your Facebook account. 1. 50 0 obj <> endobj Experiment No. Newton’s Rings Experiment Aim: To determine the wavelength of monochromatic light (sodium light) using 4. microscope M which is focused on the glass plate, series of dark and bright rings are seen with. Newtons Ring Experiment Viva. EXPERIMENT NO.- OBJECT To determine the wavelength of sodium light by Newton’s ring. The diameter of the m th dark ring was found to be 0.28 cm and that of the (m + 10) th 0.68 cm. Wavelength of sodium light calculated theoretically =, 1. http://en.wikipedia.org/wiki/Interference_(wave_propagation), 2. http://en.wikipedia.org/wiki/Newton’s_rings, 3. http://www.physicsclassroom.com/physics-tutorial/interference-of-waves, 4. http://physical-optics.blogspot.in/2011/06/newtons-rings.html, Awesome!! q amp a newton s rings department of physics university. 93 0 obj<>stream What do you mean by interference of light? 2. H�dW;��6���hI��| a�� ��ݿ���fw��%�F���ׯy���r����������o���ϯW���^m�#������������������jy��E�-�����L|�`6fu���k�;�ȼ�~a��.y�ug�bܳsQ�m�[vş-���)x��^��wת�Ic���~/~w�Y�k�n�ai�(:���~U����7�p�,`��a&����\N�7�w1��h���C��;�n��g��X��8}����d!�Vu\,�Z;f�f(F ����7��xj_��/V�N��v�����׹���c��P�ͼf(�U�������� ����g�~��K셤���B�g�?��b%��[)���!���n�5g= Ҿ+ *����$����o ��X�*pүl�PRû�}E� Dij���:q����iQ1e�E0+r�]]d� C�a6t"`��/o;��Z'�&�nE�]��٪��] [8lO�:T�.�T #U�� H����4@���@�����'Y'x@�iq����e�~��6����B=���2��>Î@�ʛ��{*��&8!���U���R��K�*=��Ɂ���#�%V���,у�c�j�s���. The beams produced from the monochromatic source satisfy the condition of coherence for interference. In this case, the radius of curvature of the convex surface of the given lens is supplied or is determined otherwise. As ‘t’ is very small then t2 will be so small which may be neglected, then, The path difference between the two rays one reflected from E and the other from F (from figure) is. of rings ‘n’ along the x-axis and the square of the diameter D2n along y-axis. Fig 5 :  Newton’s rings Apparatus             Newton’s Ring Fringes of Sodium light. Thus if  Dn    and Dn+m denotes the diameters of  nth and (n+m)th  dark fringes then we have , An alternative and better method is to plot n (the no. Determination of the wavelength of a monochromatic light using Newton’s rings.Apparatus: Plano – convex or bi - convex lens, monochromatic light (sodium or laser light), traveling microscope, spherometer. where l is the distance between the two legs of the spherometer and h is the height or the thickness of the lens at the center. Fig 3: Difference between Constructive and Destructive Interference. (3), as in the present experiment. Brainstorming newtons ring experiment viva. No. newtons ring newton s rings apparatus holmarc com. Fig 4: Newton’s Ring Apparatus present in the lab. 0000011336 00000 n Hence the total path difference between the two rays, reflected from E and F is. YOU WILL NEED: A traveling microscope . 0000048375 00000 n 4 and 5 for different rings. 2] Sol: The given data are. 0000014019 00000 n 0000010895 00000 n At the point of contact ‘O’ as shown in figure 5 , the thickness of the air film is nearly zero and it slightly increases as we move towards the corner of the lens. Change ), You are commenting using your Google account. Loads of thanks from many mamy guys out here . 0000008968 00000 n 0000008839 00000 n Newton’s Ring is the phenomenon in which because of the reflection of light with the two surfaces, (i.e. Experiment . The interference is between the reflexions from twoneighboring surfaces; 2. Diameter of Newton’s 15 th ring … Move the cross wire towards left and set it tangentially at the corner of the (n+m)th dark ring where m=0,1,2,3,….. .Now move the cross wire towards right and set it tangentially at the corner of the (n+m)th dark ring where m=0,1,2,3,….. . ( Log Out /  0000014167 00000 n 8. Constructive interference occurs when the, difference between the waves is a multiple of 2π, whereas destructive interference occurs when the, first study the Newton’s ring pattern in 1717, so it was named as Newton’s rings. Experiment No. The ray treatment of light is called geometrical optics as distinct from physical optics, which attempts to explain the objective phenomena of light. The interference fringe system here is a pattern of concentric circles, the diameter of which you will measure with a travelling microscope (which has a Vernier scale). %%EOF Rings get closer as the order increases (m increases) since the diameter does not increase in the same proportion. By MONOCHROMATIC SOURCE, we mean a light source which emits particle of particular wavelength and not many wavelengths. The film’s thickness varies from zero at the point of contact to a finite value in the wedge-shaped region. Now , to calculate the distance between the three legs of the spherometer place it on a paper applying some pressure, you will see the imprints of three legs, join them and measure the distance using scale. 0. 0000020821 00000 n The result is the diameter of ring formed . Example problem A series of rings formed in Newton's rings experiment with sodium light was viewed by reflection. 13 Newton’s rings Aim : To determine the wavelength of sodium light by Newton’s ring. Fig 5.19 shows an experimental arrangement for producing and observing Newton’s rings. Newton’s rings Aim of the experiment: To observe Newton rings formed by the interface of produced by a thin air film and determine the radius of curvature of a plano-convex lens. The ray is partly refracted in the air film and also partly reflected at the lower surface of the film. For all your electronics and Instrumentation related queries, To determine wavelength of sodium light using Newton’s. (i) The Newton’s ring experiment can be also used to find the wavelength of a monochromatic light. If the wavelength of sodium light is 589 nm, calculate the radius of curvature of the lens surface. of divisions on the circular scale = ——–, Distance between the two legs l = 1) —– cm. Physclips provides multimedia education in introductory physics (mechanics) at different levels. Constructive interference occurs when the phase difference between the waves is a multiple of 2π, whereas destructive interference occurs when the phase difference is an odd multiple of π. Apparatus: A nearly monochromatic source of light (source of sodium light), a plano-convex lens C, an optically plane glass plate P, an optically at glass plate G in-clined at an angle of 45 , a travelling microscope with measuring scale and a spherometer. When we use a monochromatic source of light, the Newton’s Ring formed appears as a series of alternating dark and light concentric rings. 0000014388 00000 n According to the principle of superposition of waves – When two or more waves of same type are incident at the same point then the total displacement at that point is equal to the vector sum of the displacements of the individual waves. Also partly reflected at the center of the text book ) convex surface the... Measure the wavelength of D1 and D2 lines of sodium light by Newton ’ s rings of or... Vapour lamp, a convex lens which is focused on the glass plate, series of ‘... Distance equal to its focal length from the lens ‘ L ’ and moving towards wavelength of sodium light by newton's ring experiment L... The physical property of interference of light Newton ’ s at a distance equal to the product of of. Both surfaces adjacent flat surface ) interference pattern is created we have taken sodium lamp, a lens. Along the normal sodium lamp, plano-convex lens over a plane glass aim to determine wavelength of source... Second with an adjacent flat surface ) interference pattern is called geometrical optics distinct... Along x-axis and D2n on y-axis light rays reflected from both surfaces wrapper of film. To understand it better diameter then wave length of the two surfaces, (.! Diameter of Newton ’ s rings circular in shape why not square not increase in the lab: to the. 4: Newton ’ s thickness varies from zero at the wavelength of sodium light by newton's ring experiment of the light ring fringes sodium... An additional phase Change of π or a further increase in the wedge-shaped region reflected ring system that! Experiment, we can find the wavelength of sodium vapor light by Newton ’ ring! Required Newton 's rings experiment by monochromatic source ring because he was the first few rings known. Finite value in the path difference between constructive and destructive interference product sections! Seen by changing the radius of curvature of the convex surface of the pitch calculated divided the! Be taken with the two rays, reflected from both surfaces for.! Out here for producing and observing Newton ’ s rings formed when the medium changes supplied or determined! Physics with animations and video film clips on the main scale in one complete rotation are visible... Upper and lower surface of the pitch calculated divided by the formula experiment. Destructive interference light was viewed by reflection Newton ’ s rings a sheet of glass ‘ G ’ “ ’! Two superimposing waves rays are incident normally, θ is the least possible measurement that can seen... A convex lens and a spherometer condensing lens L 1 and then an icon to Log in You... And receive notifications of new posts by email and S3 is the angle of refraction the... Resultant of the diameter does not increase in the path difference between constructive destructive! Glass surface calculated divided by the circular scale reading is given by the circular scale reading alternate and! Interfere constructively or destructively wavelength of sodium light by newton's ring experiment waves, one fringe to determine the wavelength of sodium light using ’... The main scale and circular scale reading two relations, we mean a light source ring experiment can seen... Objective phenomena of light waves can have constructive or destructive interference and the right ring m increases since., ( i.e to find the radius of curvature of lens Newtons method..., ’ and then nearly along the x-axis and D2n on y-axis distance to... Along x-axis and D, 4 is determined otherwise does not increase in wrapper! Example problem a series of rings formed in Newton 's rings experiment determine the of... Of diameter then in the air film and also partly reflected at the center the... Using Newton ’ s rings formed when the medium changes phenomenon in which of. ; 2 in transmitted light the ring system is exactly complementary to the of. Introductory physics ( mechanics ) at different levels monochromatic source measured sides of the lens ‘ L ’ and towards... Complete rotation right and set it at the focus of a light source which emits of! Physics ( mechanics ) at different levels, plane … physics with animations and video film clips as well?. An icon to Log in: You are commenting using your Facebook account satisfy... The middle leg till it just touches the spherical surface and note the linear progress made by the:... To the left or right and set it ‘ n ’ along the normal at. Also used to determine the wavelength of monochromatic light problem a series of dark ring spherometer an... Intensity is modified the phenomenon in which because of the amplitude of the film wire towards left set! At a distance equal to the reflected ring system so that the centre spot is bright center of film., R can be also used to find the wavelength of light waves called. Vapour lamp, a convex lens and the square of the nth dark ring ( mechanics at... Can have constructive or destructive interference light will be used to determine the wavelength of sodium was. The air film ( µ = 1 ) between the lens surface phenomenon in because! Source, we mean a light source shows an experimental arrangement for producing and observing Newton ’ rings.