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B Phase change on reflection

  1. May 10, 2018 #1
    We know that reflected light undergo a phase shift of π in EXTERNAL REFLECTION but there is no phase shift in INTERNAL REFLECTION . Does this violate Stokes Relation, which states that every reflected beam undergo of phase shift of π ?
     
  2. jcsd
  3. May 11, 2018 #2

    sophiecentaur

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    Hi and welcome to PF.
    I found this YouTube video which you may find satisfactory. What do you think?
     
  4. May 11, 2018 #3
    This video is useful in understanding of Stokes Relations but not where they are used
     
  5. May 11, 2018 #4

    sophiecentaur

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    Yes. It's not in depth but I can't see that Stokes actually contradicts the result of continuity of fields across the boundary.
     
  6. May 11, 2018 #5
    True. But it clashes with what I have studied in Interference in Dielectric Films :

    (1.) Phase changes by π in external reflection (i.e. reflection in rarer medium when the reflected ray bounces off the boundary of a denser medium).

    (2.) Phase changes by 0 (i.e. NO PHASE CHANGE) in internal reflection (i.e. reflection in denser medium when the reflected ray bounces off the boundary of a rarer medium).

    (3.) No phase change in any of refraction.

    According to Stokes Relation, point (2.) should be false but according to Interference in Dielectric Films, it should be correct.

     
  7. May 11, 2018 #6

    sophiecentaur

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    The phases involved are the result of the change in refractive index in the two directions.
    We can't argue with what you've learned about dielectric films. (I assume you were getting the right story!) so I guess you need to look at what it actually implied by this time reversal notion with rays. Time reversing involves two incident beams, which need to be the same as the emerging beams. Could that be what you are ignoring when you reckon you've found a flaw? My problem is that it all seems OK to me - but that could just be because I haven't thought deeply enough about it. :wink:
     
  8. May 11, 2018 #7

    ZapperZ

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    You might want to look at this lecture notes:

    http://web.mit.edu/6.161/www/Basic_Electromagnetics-FT07.pdf

    Zz.
     
  9. May 11, 2018 #8
  10. May 11, 2018 #9

    sophiecentaur

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    The first two pdf pages appear blank but I can see stuff further down the document.
     
  11. May 11, 2018 #10
    sorry no downward or sideward scrolling is there. Upward scrolling causes the page to reload
     
  12. May 11, 2018 #11

    sophiecentaur

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    I can read it all, afaics. Try a different browser, perhaps. I used Safari on the latest OS X.
    Edit: You mentioned sideways scrolling so you are using a mobile, I guess.
     
    Last edited: May 11, 2018
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