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Have electromagnetic waves any polarity?

  1. Jun 18, 2010 #1

    My doubt is how can the EM waves interact with an electron, i.e.,
    electron is a particle with negative charge.. have EM waves any charge to attract or to repulse an electron ? :confused:

    An example is the microwaves oven when waves interact with water molecules.

    Thanks :smile:
  2. jcsd
  3. Jun 18, 2010 #2
    Remember, charges interact with each other via the electric field.
  4. Jun 18, 2010 #3
    very good... but the electric field (or magnetic) on EM waves has something like positive or negative signals?
  5. Jun 18, 2010 #4
    The energy of the wave is measured in the 2D plane perpendicular to the direction of the field. There is 2 orthogonal dimensions and linear combinations of these. So the polarization of the wave is the direction (within this 2D plane) the field is moving in.

    If you attach a string to an object and think of the string as the electric field, you can shake the string up and down or left and right or any linear combination of this. That is polarization.
  6. Jun 18, 2010 #5
    why electromagnetic waves doesnot require any medium to propagate
  7. Jun 18, 2010 #6

    Only the electron particle can emit and interact with EM waves ?
  8. Jun 19, 2010 #7
    protons by them selves can emit photons , as well as other particles .
    And some particle anti-particle collisions .
  9. Jun 20, 2010 #8
    But can an EM wave emitted by the proton interact with electron ?
  10. Jun 20, 2010 #9
    it could interact through the gravitational force , I wonder how the magnetic field of the electron would permeate through a photon's localized energy , if it would be different than permeating through a vacuum .
  11. Jun 20, 2010 #10
  12. Jun 20, 2010 #11


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    That's basically the Quantum Electrodynamics description of Hydrogen atom right there. Proton emits photons that are absorbed by electron, and vice versa.

    Virtual off-the-shell photons, mostly, by the way.
  13. Jun 21, 2010 #12
    does a photon interact with electric and magnetic fields .
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