Deflect Light: Electromagnetic Waves & Magnetic Fields

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Discussion Overview

The discussion centers on whether electromagnetic waves, specifically light, can be deflected by a magnetic field. Participants explore the theoretical and practical implications of this interaction, referencing concepts like the Faraday effect and the conditions under which such deflection might occur.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions if light can be deflected by a magnetic field, drawing a comparison to how electron beams are affected by electric fields.
  • Another participant asserts that light does not get deflected in free space by magnetic fields, but rather behaves like a magnetic dipole and rotates in the presence of an external magnetic field.
  • The Faraday effect is introduced as a phenomenon where light interacts with a magnetic field, but it is noted that this requires a material medium and does not occur in free space.
  • A later reply acknowledges the initial description as overly simplistic and points out the lack of examples of deflection in free-field scenarios.

Areas of Agreement / Disagreement

Participants generally agree that light does not get deflected by magnetic fields in free space, but there is some debate regarding the conditions under which light can interact with magnetic fields, particularly through the Faraday effect in a material medium.

Contextual Notes

Limitations include the dependence on the presence of a material medium for the Faraday effect and the lack of observed instances of photon-photon scattering in free space.

Lesnick
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Can electromagnetic waves e.g. light be deflected by a magnetic field?
 
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If you mean: "can a light beam be deflected by a magnet" like an electron beam gets deflected by an electric field - then the short answer is no.
https://www.physicsforums.com/archive/index.php/t-282656.html

If you look at how the magnetic field of the light wave is oriented (transverse), you'll see that it behaves in an external magnetic field much like a magnetic dipole does - by rotating.

This is called the Faraday effect.
Exploited in electrical polarizers.

Photons do feel the EM interaction though, and can, in principle, scatter from other photons.
However, afaik, it has yet to be observed.
 
Last edited:
Simon Bridge said:
If you look at how the magnetic field of the light wave is oriented (transverse), you'll see that it behaves in an external magnetic field much like a magnetic dipole does - by rotating.

This is called the Faraday effect.

You need a material medium for this interaction. It doesn't happen in free space.
 
That's right.
The description was a bit glib.

No examples of free-field deflections available.
 

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