Ambiguity of Curl in Maxwell-Faraday Equation

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SUMMARY

The discussion centers on the ambiguity of the electric field derived from the Maxwell-Faraday equation, specifically the equation ∇ × E = -∂B/∂t. Participants highlight that the curl operator is not injective, leading to multiple potential solutions for the electric field unless specific boundary or initial conditions are applied. The uniqueness of solutions in partial differential equations (PDEs) is emphasized, particularly in relation to the Helmholtz theorem, which necessitates both curl and divergence conditions. The conversation also touches on the implications of using unrealistic scenarios, such as a circular current loop generating a magnetic field without external influences.

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  • Understanding of Maxwell's equations, particularly Faraday's Law.
  • Familiarity with vector calculus, including curl and divergence operations.
  • Knowledge of partial differential equations (PDEs) and boundary conditions.
  • Basic concepts of electromagnetic fields and their interactions.
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  • Explore the implications of Jefimenko's equations for electromagnetic fields.
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Physicists, electrical engineers, and students of electromagnetism seeking to deepen their understanding of the relationship between electric and magnetic fields, particularly in the context of Maxwell's equations and PDEs.

  • #31
vanhees71 said:
Again, a vector field is only completely specified when giving it's curl and its divergence together with the boundary conditions. Look for Helmholtz's fundamental theorem of vector calculus!
Do you need any clarifications with the notions in #23 and #27? (and I'm not trying to be rhetorically snarky)
 
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  • #32
As I said, I don't see the physics behind your artificial assumptions. You need to solve the complete set of Maxwell equations, not just one!
 
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  • #33
vanhees71 said:
You need to solve the complete set of Maxwell equations, not just one!
I agree completely with this and all of my comments are assuming that we are looking for solutions to all of Maxwell's equations.
 
  • #34
You don't need relativity or tensors to get a grip on this problem. You do need to use dynamic rather than static potentials; for example, the familiar E -= -∇V changes to E = -∇V - μ ∂A/∂t
where A is the vector potential such that H = ∇ x A = B
and V is the scalar electric potential;
and Poisson's equation changes to ∇2V = -ρ/ε - μ ∂/∂t (∇⋅A) etc.
If you try to use static potentials you get that the E field around even a time-varying current is zero.
EDIT: I was assuming a long wire but what I said can be applied to your coil also.
The idea of retardation potentials is included in what I said FYI.
 
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