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Electric field and light and stuff

  1. Jan 21, 2009 #1


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    Is there any effect on a light beam in a strong electric field? I'm thinking to a laser beam that passes trough a very long parallel plate capacitor. And what if we have an nonuniform, electric field, like in the case of a very large metallic sphere at a high electric potential? Thanks!
  2. jcsd
  3. Jan 22, 2009 #2


    Staff: Mentor

    Maxwell's equations are linear, so I don't think there would be an effect. The only way I could see there being an effect would be in the presence of a nonlinear medium instead of free space.
  4. Jan 22, 2009 #3
    I would have thought that there would be no effect in a steady electric field but there might be a very very small effect during the build up of an electric field or an alternating electric field.
  5. Jan 22, 2009 #4


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    Quantum mechanics predicts that in a strong enough electric field, two light quanta of sufficient energy can turn into an electron and a positron. Actual real particles with mass, fermionic spin, charge and all.

    Someone will no doubt point out that other conditions are needed, but the equations indicate that the probability of particle creation depends on the electric field strength.
  6. Jan 23, 2009 #5


    Staff: Mentor

    That is a good point. I should emphasize that I was speaking in strictly classical terms.
  7. Jan 23, 2009 #6
    If the field is Very strong, one could also add the effect of gravitational bending of the beam passing close to the region of higher field, but it would be due to the field's high energy density and not to the fact that it's an electric field.
  8. Jan 23, 2009 #7
    Electromagnetic fields are not self interacting, per Dalespams post #2.

    As lightarrow points out, there is a small gravitational interaction since the electromagnetic fields (the light beam and the electromagnetic field) both carry energy. (energy is a component of the Einstein stress/energy/momentum tensor.)

    Another way to think of the answer:all radiation is affected by gravity...following the above logic.
  9. Nov 30, 2009 #8
    sorry but have any of you heard of the Faraday effect?

    light traveling through a medium IS effected by magnetic field and I presume, similarly an electric field.


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