Polarisation Definition and 122 Threads

IPS (International Pol Scale) is a price adjustment scale described in the rules of the Sugar Association of London. It defines incremental price premiums and penalties applied to sugar above 96 degrees polarisation. This scale equates that the sugar contains 96% sucrose'

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  1. entropy1

    B Entanglement, correlation and randomness

    I was wondering. In this example I use polarized photons, but maybe it is applicable to electrons and spin also. We can prepare two completely unentangled polarized photons, and send them in opposite directions to two detectors preceded by a filter at particular angles. Both of them will show a...
  2. JohnGaltis

    Conceptual Question about Polarisation and Intensity/

    Homework Statement Consider a beam of unpolarised light incident onto air from a crown-glass with a refractive index of 1.52. Given that the incident light intensity has a power of 10mW, find the minimum incident angle when the power of the refracted light becomes zero. Homework Equations I...
  3. dbertels

    B Bell's Inequality && polarisation for the layman

    My previous thread on this topic got a bit messy as the gist of the argument was in the middle of the thread and turned out wrong. Hence this new updated version. One of my favourite articles on Bell's Theorem can be found at...
  4. dbertels

    B Proving entanglement using polarisation & Bell's Inequality

    I've seen some articles using particle spin experiments to 'prove' that the results violate Bell's inequality and consequently local reality. I've also seen stated that the same experiments can be done using other particle attributes such as polarisation. I can see how with polarisation, you...
  5. entropy1

    Does a polarisationfilter do a measurement?

    Consider a measurement of a photon after it has passed a polarisationfilter. Does the photon jump in a (polarisation-)eigenstate by passing the filter? Does the filter do a measurement? Is the filter part of the entire measurement?
  6. entropy1

    Probability of entangled photons passing filter independent?

    Consider two polarisation-entangled photons A and B fired at two polarisationfilters that are at a certain angle α. Are the probability that A is passing its filter and the probability that B is passing its filter indepedent probabilities? I am aware that is probably an incredibly stupid...
  7. gracy

    Understanding Dielectric Polarisation: Transformation of Dipoles and Charges

    A dielectric is placed between two capacitors ,How (a) gets transformed into (b) Where did all the dipoles present in picture (a)go?And from where the negative and positive charges appeared inside the dielectric in picture (b)
  8. entropy1

    Are photons passing a polarization filter randomly?

    This may be a dumb question, but maybe someone can help me out: Consider a pair of entangled photons A and B, fired at respectively Alice and Bob who both let it go through a polarisation filter at different angles. Now Alice establishes that half of the photons get through her filter, and half...
  9. sergiokapone

    Can a rotating dielectric disc be polarized?

    Can a rotating dielectric disc be polarized? No external electric or magnetic field .
  10. entropy1

    Bell-state entanglement swapping and retrocausality

    I thought there were already some posts about this, but I can't find them.:frown: In this article of Anton Zeilinger et al. they perform an experiment which suggests FTL or retrocausal influence. Alice and Bob both produce their own polarisation-entangled photon pair, both send one photon of...
  11. gokhul

    Polarisation of magnetic field

    Does magnetic field of lightgets polarised when electric field polarised when passed through a polariser
  12. 1

    A way to plastically flip a circular polariser?

    hi, I'm currently talking about light, and I'm trying to find out if there is a material or a method that can flip a polariser's polarisation... ie, if i apply a current, then this crystal changed from a clockwize polariser to an anti-clockwize polariser, and it is either a plastic or elastic...
  13. E

    Why is unpolarized light halved in intensity when polarized?

    I would appreciate if the explanation didn't derive this phenomenon using Malsus' Law exclusively and would go into the horizontal and vertical components of polarized light, and how the blocking of the horizontal components results in a halved intensity...so more of a geometric explanation...
  14. G

    Do observables for polarizers at different angles commute?

    Hi. We can write a polarised photon as ##\left|\alpha\right\rangle=\cos(\alpha)\left|\updownarrow\right\rangle+\sin(\alpha)\left|\leftrightarrow\right\rangle##. Trigonometry gives us $$\left\langle\alpha | \beta\right\rangle=\cos(\alpha)\cos(\beta)+\sin(\alpha)\sin(\beta)=\cos(\alpha-\beta)$$...
  15. andrewkirk

    Polarisation destroying interference pattern for double slit

    I have been trying to mathematically explain the empirical result that putting orthogonal polarisers (quarter-wave plates) behind the two slits of a double-slit setup will erase the interference pattern. The trouble is, my analysis predicts an interference pattern. I must have made a silly...
  16. sergiokapone

    Field inside spherical hole inside dielectric

    Let we have a dielectric with field ##E## inside and with a little hole. I have problem. I get a two different answers on this problem, and I try to understand which one of them correct. As mentioned in http://www.feynmanlectures.caltech.edu/II_11.html#Ch11-S4 (11.25), the electric field in...
  17. Quotes

    Which Molecule Type is More Polarizable in a Uniform Electric Field?

    Which of them 1.Polar Dielectric molecule 2. Non Polar molecule Will get polarized to a greater extent when kept in a uniform electric field? (I think its the 2nd one because force applied has to stretch the positive and negative charge centres apart to polarise it.. But at the same time for...
  18. Jilang

    Is polarised light a result of destructive interference?

    This question is prompted by a recent discussion I have been following regarding the insertion of a 45 degree angle polariser between two polarisers at 90 degrees to each other. The insertion of the filter seems to restore missing components which would suggest that those components were present...
  19. P

    Strange thing happens with the surface polarisation charge density

    This confusion is about the following problem: Suppose the entire region below the plane z=0 is filled with uniform linear dielectric material of susceptibility ##χ_e##. Calculate the force on a point charge q situated a distance d above the origin. Now, this problem is done in Griffiths'...
  20. Dadface

    Entangled photons and polarisation.

    I have been looking up the practical details of certain quantum eraser type experiments and got stuck on a couple of points. I refer to a particular experiment which can be found by googling: "A DOUBLE SLIT QUANTUM ERASER EXPERIMENT" (Sorry I don't know how to include the address) In...
  21. Q

    Light polarisation and photon spin

    What is the link between the polarisation of light and photon spin?
  22. KiNGGeexD

    Polarisation past paper question

    Question For (i) I assumed that the light was plainly polarised as there is only a difference in amplitude For (ii) There is a negative sign infront of the amplitude which I ignored as it doesn't change the polarisation but one is cos and the other is sin, so there is a phase shift of...
  23. S

    Polarisation of reflected light

    Hi, I have a question regarding the projection of polarised light onto a screen, such as commonly used in 3D or VR cinemas. I'm only concerned with linearly polarised light for the moment. I understand that when light undergoes reflection the polarity is altered. I've attached a diagram...
  24. StevieTNZ

    Linear to Circular Polarisation Questions

    I have some questions referring to wave plates. We have an entangled pair of photons as |H>|V> - |V>|H> and both go through 22.5 degree orientated half-wave plates. |H> is converted to |45> and |V> is converted to |135> (so the description is now |45>|135> - |135>|45>). So inputting the...
  25. B

    Polarisation of photons exiting a birefringent crystal

    Homework Statement The problem is taken from A Modern Approach to Quantum Mechanics by Townsend, and is stated as follows: The answer given in the back of the book is 0.12, though I have not managed to get this result. Homework Equations Classically, light traveling through a crystal...
  26. E

    Is Circular Polarisation the Same as Linear Polarisation?

    I have read about polarisation... just a little ques about concept... in case of circular polarisation there is 90 degree phase difference between the two v and h, e field component... right... and in case of linear polarisation the e field is restricted to oscillate in only one plane...
  27. Q

    Understanding Wave Polarisation: Intensity Changes and Filter Effects Explained

    I have two queries: - if unpolarised light passes through a polaroid filter so that light coming out of the filter becomes polarised, would intensity (brightness) of the light become reduced as a result? - if you have a polarized wave, and it passes through a filter that has a gap which is...
  28. H

    Longitudional electro magnetic waves and linear polarisation

    Hello, Are longitudinal EM waves ( I know they exist) any different from linearly polarised waves we learn about in antennae theory Just to be clear http://www.antenna-theory.com/basics/polarization.php defines linear polarisation pretty clearly in the context i am talking about
  29. S

    Can Heat Waves Be Polarized and Controlled in Direction?

    we know that heat is caused by vibration of molecules. the vibration by nature of molecules is random. but in as in polarized light can we give heat that is vibration a particular direction. then this vibration i call polarized heat has varying temp at various angles. can this be actually...
  30. F

    How to find the amplitudes and polarisation of travelling waves

    Homework Statement Plane monochromatic waves are propagating in free space parallel to the x-axis in both positive and negative directions. At the origin the fi eld strengths are given by: Ez = E0 cos wt Ey = 3E0 cos wt cBz = E0 cos wt cBy = E0 cos wt Find the amplitudes and...
  31. M

    Move or attract large/heavy materials using polarisation

    I was just wondering if it was possible theoretically to move or attract large/heavy materials using polarisation. For example I've heard examples that if you have a charged rod ,and you bring it close enough to pieces of paper the charge on the rod will polarise the paper and then if that...
  32. R

    Determining the polarisation state of the waves.

    Homework Statement E(z,t) = E_{0x} \sin (kz - wt - \frac{\pi }{12}) - E_{0y} \cos (kz - wt + \phi + \frac{\pi}{12}) E(z,t) = E_{0x} \sin (kz - wt - \frac{\pi }{3}) - E_{0y} \sin (kz - wt + \frac{\pi}{6}) The Attempt at a Solution For the first and second problem, I set t and z both to 0, so...
  33. M

    Why reflection causes polarisation of light

    Hello all I know that polarisation of light can occur from reflection, and when the reflected ray is 90degrees from the refracted ray the relfected light is 100% plane polarised. So, my question is why is it that reflection causes polarisation of light? Thanks
  34. J

    Why and how chiral molecules rotate plane of polarisation?

    I have been studying stereochemistry and it says that optically active molecules(chiral molecules) rotate plane of polarisation. I suppose that's because of the electrons in the molecule. I know that all molecules can rotate the plane of polarisation but when achiral moelcules are present in...
  35. StevieTNZ

    Polarisation Rotators and Measurement

    When we use polarisation rotators to measure certain polarisations for entangled photons, the photon usually meets a polarised beam splitter after. When we detect in the |H> or |V> basis, does that mean the photon is in |H> or |V>? What has happened to the polarisation we were measuring...
  36. G

    Linear polarized light and polarisation

    hi if you have linear polarized light and you have a metal grid and the angle between the e-vector and the metal grid is 30°. now you split up the e-vector in one component parallel and one component perpendicular to the metal grid. okay. so the component of the wave, that survives this...
  37. H

    Bell inequality experiments and photon polarisation issue

    I am confused by the role of photon polarisation in Bell inequality experiments. The original logic of EPR as I understand it is based on the HUP such that QM predicts that measurement of momentum on one particle should affect the measurement of position of the other particle. Yet across...
  38. J

    AS Physics - Polarisation Problems.

    Hey guys. I need some help on understand a few concepts and have some questions 1. How is light polarised when it is reflected? 2. Are there different amounts of light vibrating in each direction, or is it equal? 3. From my revision guide: "If you direct a beam of unpolarised...
  39. L

    What creates polarisation field when -div(P) = 0?

    Homework Statement Context: Between the two conducting cylinders of a coaxial cables, there is a dielectric hollow cylinder. There is free static charge Q on a length L of the inner conductor, and free static charge -Q on a length L of the outer conductor. Upon calculating that the...
  40. StevieTNZ

    Is Bohmian Mechanics Compatible with Polarisation Experiments?

    I was thinking: if you send light through a 45 degree filter (D filter), and then sent that light through another D filter, because it is now in superposition of V+H state, and according to 'Beyond Measure', light in that state (left circularly polarised) would go through the 2nd filter 100% of...
  41. L

    The average value of cos^2(phi) is 1/2.

    Hi,Homework Statement I have the following question: I found two formulas given for the intensity after polarised light went through a polarisation filter. Homework Equations I_{1}=I_{0}*\frac 1 2 and I_{1}= I_{0}*cos^{2}(\phi) The Attempt at a Solution Well I don't know when to use...
  42. T

    Polarisation in dielectrics, anyone?

    I have been studying polarization in dielectrics recently. I got stuck after coming to Claussius Mossoti equation. I can't understand it's importance. I read that it is used to determine molecular structure but how exactly? I've just joined this forum, hope someone can help. :) TIA P.S: Sorry...
  43. J

    How can polarisation by angle 45 degrees be represented in quantum mechanics?

    Hi there, mathematician learning a little QM here. I've been watching a few of these lectures: http://www.youtube.com/watch?v=LBFBQr_xKEM&feature=relmfu The lectures are good, a little slow paced for me, but clear at least. He starts talking about polarisation in the last half of...
  44. H

    Interference & Polarisation Questions

    1.in an intrfrnce expmnt. wit monochromatic light of wavlngth 6000 AU only 50 fringes are observable.estimate d coherence of d source. 2.show a circularly polarised lght is eqvlnt to 2 mutually perpendicular plane polarised lt wit a phase diff of pie/2. 3.fringes of equal inclination are...
  45. M

    Kirchoff's radiative balance law and polarisation of emitted light

    I'm looking at a surface at an angle. Light reflected to me is polarised (Fresnel), does this mean light emitted to me from the surface is also polarised? I've been told that ocean emission is polarised (when looking at an angle) because of Kirchoff's law of radiative balance (emissivity =...
  46. Y

    Full knowledge of polarisation angle.

    Reading around the subject, I get the impression that it is impossible to have full knowledge of the polarisation angle of a photon. For example is a linearly polarised photon passes through a vertical polariser it is said to be "vertically polarised" on exiting the polariser, but in fact all we...
  47. M

    Measuring the Polarisation of Light

    Maybe this is a trivial question, I'm not sure, but when you measure linearly polarised light, such as that in the CMB which component of the light is 'measured'. By this I mean is it the oscillating electric field or the oscillating magnetic field that is oscillating in the direction of the...
  48. H

    Why Does Parallel Radiation to Magnetic Fields Exhibit Circular Polarisation?

    Homework Statement A particle of charge 'q' and energy 'E' which experiences an acceleration 'a', emits electromagnetic radiation. Show that the radiation from this particle which is emitted parallel to the magnetic field is expected to exhibit circular polarisation. The Attempt at...
  49. V

    Surface plasmons not exist for transverse polarisation?

    surface plasmons not exist for transverse electric polarisation? and only exist for transverse magnetic polarisation can anyone help meeeeeeeeeeeeeeeeeeee please
  50. N

    Polarisation vector vs spin vector

    In what relation to each other are the direction of spin vector and direction of polarisation vector... for example of a photon ?
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