Do Electric and Magnetic Fields Affect Electromagnetic Waves?

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Discussion Overview

The discussion revolves around the interaction between electric and magnetic fields and electromagnetic waves, exploring whether these fields can affect electromagnetic waves. The scope includes theoretical considerations and conceptual clarifications regarding the nature of fields and their interactions.

Discussion Character

  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants assert that electric and magnetic fields do not exert forces on electromagnetic waves, citing the classical statement of the linearity of electromagnetic fields.
  • Others question this view, suggesting that fields can interact with one another, using examples such as changing electric fields producing magnetic fields.
  • A participant notes that electromagnetic waves have no charge, which may contribute to their lack of interaction with electric and magnetic fields.
  • There is mention of electroweak fields that can carry charge and may interact differently with electromagnetic fields.
  • One participant argues that gravity can affect electromagnetism, challenging the notion that no forces act on electromagnetic waves.

Areas of Agreement / Disagreement

Participants express differing views on whether electric and magnetic fields can affect electromagnetic waves. While some maintain that they do not interact, others provide counterexamples and suggest that interactions can occur under certain conditions. The discussion remains unresolved with multiple competing perspectives.

Contextual Notes

Participants reference classical electromagnetic theory and Maxwell's equations, but there are unresolved nuances regarding the conditions under which fields may or may not interact.

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why do electric and magnetic fields have no effect on an electromagnetic wave?
 
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Electric fields exert forces on charges. Magnetic fields exert forces on currents (or moving charges.).

Neither field exerts forces on electric or magnetic fields. This is the classical statement of the linearity of EM fields and to a very large degree it is accurate.
 
Is it because the electromagnetic wave has no charge?
 
faiz4000 said:
why do electric and magnetic fields have no effect on an electromagnetic wave?

A wave is also a field. A field does not act on another field just like a force does not act on another force. :)
 
Hernik said:
Is it because the electromagnetic wave has no charge?

Yes. But there is an exception; some electromagnetic (electroweak) fields can carry charge but these fields are almost never observed directly.
 
I think I am not sure I agree.

A field is just a set of numbers at each point in space and time. We think of electric and magnetic fields, but the same formalism can be used elsewhere: in a previous message I described wind as a velocity field. So there is no reason a field cannot act on another field, and there are counterexamples: a changing electric field produces a magnetic field.
 
Vanadium 50 said:
So there is no reason a field cannot act on another field, and there are counterexamples: a changing electric field produces a magnetic field.

An electric field cannot act on another electric field. The same holds for other classical force-fields anyway.
 
That's true, but the key word is "electric". It's a statement about the kinds of fields, not a statement about fields.
 
Vanadium 50 said:
That's true, but the key word is "electric". It's a statement about the kinds of fields, not a statement about fields.

This is correct in the general case.

When photons are involved and we have Maxwell's equations, the charges don't exert forces on the fields only the other charges.

The electroweak fields are different. The W is a charged force carrier. This means the electroweak fields do exert forces on charges, on EM fields, and on itself.
 
  • #10
So an electromagnetic field couldn't say, disturb light, or any other frequency on the EM Spectrum?

Any one force not having an affect on the other is incorrect, look at gravity, it has an affect on electromagnetism.

Michael
 

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