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The magnetic field of a photon

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  1. Sep 24, 2015 #1

    bobie

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    Do different photons with different frequencies/energies have same magnetic field?
    Does the fact that all photons have same magnetic angular momentum imply a positive answer?
     
  2. jcsd
  3. Sep 24, 2015 #2

    Drakkith

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    What do you mean by 'the same'? The magnetic field also varies with time, so higher frequency photons have magnetic fields which vary faster over time.
     
  4. Sep 24, 2015 #3

    sophiecentaur

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    I'm not sure it is even a valid thing to try to describe a quantum particle in terms of a classical notion like a field.
    I realise that may be an annoying answer but you may need to accept it.
     
  5. Sep 25, 2015 #4

    bobie

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    The question was rhetorical of course, different photons have different linear momentum hf/c, why should the all have same angular momentum = 0.159 h ?
     
  6. Sep 25, 2015 #5

    Drakkith

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    Rhetorical, or pointless?
     
  7. Sep 25, 2015 #6

    BvU

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    Funny thing is that we also have lots of threads where we explicitly NOT want the photon described as a particle (e.g. here), because it isn't .

    Even after all these years I kind of like to keep an open mind and be satisfied that we all we can do is describe a big part of the behaviour of a photon in terms we also use for particles. And a (perhaps bigger :smile:) part in terms of electromagnetic fields, quantum states and what else humanity has come up with over the years. But then, I'm only an experimental physicist...


    [edit] oh, and bobie: I think the answer to your question has to do with the coupling of E and B field for an electromagnetic wave. I need to re-read big parts of Jackson before I can really answer, so I'm glad to be watching this thread. Who knows what may be added yet !
     
  8. Sep 26, 2015 #7

    sophiecentaur

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    I think the problem here is that you / they are assuming that the EM phenomenon is 'in fact' particulate. That approach is bound to bring in difficulty because a classical Field has to be 'somewhere' and relate to a position and extent. When you have a photon that is nowhere, in particular, until it is interacting with matter (that's the quantum aspect) you can't talk in terms of the fields. That applies even when discussing a quantity like angular momentum
    You have to treat the EM phenomenon according to the situation you are studying. It's more than just the old Duality thing that we learned in the beginning of our Advanced Physics courses. So it is not sense to want to describe a photon NOT as a particle. You need to step back and choose to describe EM as particle or wave - those are the options.
    I am surprised at your making that comment in the light of many of the comments you have made in the past which imply a distinct nature between the two approaches - but here, you appear to bolt them together again. ?? :confused:
     
  9. Sep 26, 2015 #8

    Nugatory

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    I don't think there's any way of getting consistency AND general applicability into an English-language handwave about photon characteristics....
     
  10. Sep 26, 2015 #9

    Drakkith

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    o:)
     
  11. Sep 26, 2015 #10

    sophiecentaur

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    I think Nugatory has summed up the situation so far. :biggrin: (No egg on any faces here)
     
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