# Talk:Newton's rings

WikiProject Physics (Rated C-class, Mid-importance)
This article is within the scope of WikiProject Physics, a collaborative effort to improve the coverage of Physics on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.
C  This article has been rated as C-Class on the project's quality scale.
Mid  This article has been rated as Mid-importance on the project's importance scale.

This needs some figures, and connections to other articles on wave optics and thin film interference. It's interesting that one of the external links predicts that the center is dark, while the other one has a photo showing the center being bright! From my own experience, the theory is only a rough description of the reality, and the pattern depends a lot on the angle from which you view it, and on how hard you press the two surfaces together. The page at [1] suggests cleaning: "If the centre fringe is not dark, try polishing the lens and flat with a spectacle cleaning cloth."--Bcrowell 05:56, 8 December 2005 (UTC)

The center really is dark. I saw it myself in a demonstration. The dark point is really really small, inside the big bright first circle. When the instruments used aren't of very good quality, or the photograph taken is of insufficient resolution, I can imagine that you can't see the dark point. Aphexer (talk) 09:50, 22 December 2007 (UTC)

Perhaps worth adding how one uses the phenomenom to make better lenses - as Newton says Newton did. Midgley 02:22, 20 March 2006 (UTC)

The center should be dark because that is the point where the two glass objects are touching, so there are no two reflections to interfere.

Looking at the figure with annotations, it looks like the two comments on even and odd multiples of lambda/2 should be switched: there is a phase shift of pi when the light is reflected on the optically denser medium. So, on the lower boundary there is a phase shift of pi, on the upper boundary there is no shift, so the path difference for constructive interference should be even multiples of lambda/2. — Preceding unsigned comment added by 161.53.70.102 (talk) 08:56, 15 January 2014 (UTC)

The figure for "Simulation of Newton Rings under reflected light of different wavelength" has the wrong wavenumbers displayed. They should be 10 times larger. LDCorey (talk) 05:05, 1 April 2014 (UTC)

The equation relating the distance from the center, X, to the thickness, t, is incorrect. The X should be squared, right? — Preceding unsigned comment added by 151.190.40.1 (talk) 17:10, 6 June 2014 (UTC)

The diagram is incorrect. The attitude of the waves reflected on the inside of the glass should be inverted while the attitude of the waves reflected of the second glass should not. This means the distanced should also be fixed. Also the interference pattern is dark if the distance is a multiple of 1/2 lambda, and light if its a multiple of 1/2 lambda minus 1/4 lambda.99.239.233.16 (talk) 01:10, 22 October 2014 (UTC)

""an interference pattern is created by the reflection of light between two surfaces—a spherical surface and an adjacent touching flat surface"" The page later states that the effect can be observed between the two flat surfaces of sandwiched plano-conex lenses, partially contradicting the first statement. Arguably, of course, no surface would ever be perfectly planar and therefore all surfaces are partially spherical. But this effect can also be observed when an optical filter or window is placed in front of a CCD chip and illuminated with coherent light. Planar:planar. — Preceding unsigned comment added by 141.34.3.183 (talk) 15:54, 3 March 2016 (UTC)

## Newton's notion of light

It should be noted that Newton thought that light consists of particles rather than waves. So I'm surprised that its named after Newton (I knew the phenomenon of interference rings but I hadn't heard this name for this special case before I came across this article). 193.154.191.21 01:37, 16 February 2006 (UTC)

What 'Newton thought' was not constant. He tried at one time to make a wave theory work (as in Opticks, Question 13). He even realised that red had a longer wavelength than violet. In the end he gave up the wave theory for the particle theory [2]. --Heron 19:34, 16 February 2006 (UTC)
I read somewhere that Newton gave the explanation that the particles of light were disturbed by the glass and vibrated. That is like the explanation of the neutral kaons,
K0
and
K0
, oscillating from one to the other after passing through a target. He just had the wrong particle. David R. Ingham (talk) 20:55, 16 November 2009 (UTC)

## Diffraction Pattern

Don;t know if this would be relevant, or ifmy understanding is flawed so thought I should post here first. Am I correct in my understanding that Newton's Rings are a form of a diffraction pattern? Just wondering if anyone else thinks this article might be enhanced by a brief mention of that or a link to the wiki article on diffraction. :) Weenerbunny 17:40, 7 July 2006 (UTC)

## Equation

The equation is off. I will change it ASAP, but I am not very good at the formulas. Here is the link to the page, if anyone else wants to change it, you may. http://www.fas.harvard.edu/~scdiroff/lds/LightOptics/NewtonsRings/NewtonsRings.html It is the second equation, the one for the mth ring. -Hairchrm 20:12, 3 November 2006 (UTC)

## Scanning issues

Newton's rings are a common annoying problem when scanning transparencies. I don't have the time or expertise to explain the solution, but I've seen some scanner operators spread a liquid gel onto a tranny before taping it down to a drum scanner, for example. The other option is to mount a tranny in a special mounting bracket so that the tranny sits in free air instead of next to glass when it's inside a scanner. Dave Laird 06:52, 16 February 2007 (UTC) What is the equation to find the approximate width of the m-th dark fringe? What is the equation to find the approximate width of the m-th bright fringe?

## Interference - diffraction vs reflection

Weenerbunny, Diffraction patterns are formed by interference of light waves scattered by narrow slits or lines, Newton's Rings are formed by interference of light waves reflected from different surfaces. Same effect, but different reasons why waves follows the slightly different path lengths that result in light and dark zones - constructive and destructive interference. Gil johnson 22:18, 29 April 2007 (UTC)

## Optical coupling

Would it be accurate to say that if the two surface come in contact, the central ring is where the surfaces are optically coupled? —Ben FrantzDale (talk) 20:28, 29 July 2008 (UTC)

No. This is a different phenomenon. David Spector (talk) 20:29, 22 July 2013 (UTC)

## At what height the dark central will turn to bright fringed at newton ring?

Give a comment —Preceding unsigned comment added by 60.49.174.6 (talk) 05:01, 22 November 2008 (UTC) WHY SHOULD BE TWO SOURCES BE MON OCHROMATIC —Preceding unsigned comment added by 220.225.244.114 (talk) 09:25, 19 January 2010 (UTC) IF WHITE LIGHT IS USED INSTEAD OF MONOCHROMATIC LIGHT THEN equation 2µt=(2n-1)λ/2 will be satisfied for different values of n with different values of λ. SO RINGS WILL APPEAR COLOURED . WHITE LIGHT CONSISTS OF 7 COLOURS OF DIFFERENT WAVELENGTH. diameters of newtons ring is proportional to wavelength of different colours. As we know that λr>λv therefore diameter of violet ring of same order will be smallest and those for red ring will be largest. and diameters of other coloured rings will be in between. Due to overlapping of rings of different colours over each other , only first few coloured rings will be clearly seen while other rings cannot be distinguished verly accurately. --Swathy 2592 (talk) 02:51, 6 May 2011 (UTC)

## WHY NEWTONS RING ARE CIRCULAR AND CONCENTRIC  ?

ANS :intensity of rings formed depends on the thickness of air column b\w the lens and glass plate.

```    and the locus of the points having same thickness of air column is circle
,with the center as the point of contact b\w the glass &lens
```