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Light wave orientation

  1. Oct 26, 2008 #1
    Electromagnetic radiation has a magnetic aspect at 90 degrees to the electro aspect of the radiation.

    We see light, experience heat, use radio, x-rays, microwaves, etc.

    Can someone please help me with this question about the above:

    - Which way is the magnetic aspect orientated to the electro aspect? Clockwise or anti-clockwise?
  2. jcsd
  3. Oct 28, 2008 #2


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    If the radiation is traveling towards you, the magnetic field is 90 degrees anti-clockwise from the electric field.
  4. Oct 29, 2008 #3
    Thanks Redbelly. How do you know that though? Is there some info on this?
  5. Oct 29, 2008 #4


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    Ultimately, it's a consequence of Maxwell's Equations, though I myself don't know how to derive it. I just looked it up in a textbook from when I took a class in optics; the book is "Optics" by Hecht & Zajac, though I think newer editions just list Hecht as author.

    Also found this on the web:


    This might lead you to more info:
  6. Oct 29, 2008 #5
    Thanks again RedBelly. You couldn't transcribe the paragraphs from your textbook that mention which direction the magnetic aspect is to the electro aspect? If it mentions why that would be great too. I looked at the sites you gave but I couldn't really find this specific info.

    I know that an electric current through a wire produces an anticlockwise magnetic aspect to the direction the current flows. I presume that a current of anti-electrons through an antimatter wire would produce a clockwise magnetic aspect to the direction of current flow.

    Photons in our matter world tend to interact with electrons rather than the protons.
    As opposites attract I would have expected photons to have an opposite magnetic aspect to electrons; not the same.

    So when you said they were the same I was surprised. This is why I really need to know if there is some experimental evidence of the orientation.
  7. Oct 30, 2008 #6


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    Well, to be honest I just looked at the figure in the book, and didn't follow the derivation. It has been more than 20 years since I had the class.

    While I would imagine there is experimental data on the relative orientation of E and B in electromagnetic waves, I am not specifically aware of what that data is.
  8. Oct 31, 2008 #7
    Thanks for trying to help Redbelly. Hopefully someone else might know?
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