Ambiguity of Curl in Maxwell-Faraday Equation

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The discussion centers on the ambiguity of determining the electric field from a changing magnetic field as described by the Maxwell-Faraday equation. It highlights that while Faraday's Law provides a relationship between the curl of the electric field and the rate of change of the magnetic field, it does not uniquely determine the electric field without appropriate boundary and initial conditions. The importance of these conditions is emphasized, as they are essential for achieving a unique solution in the context of partial differential equations. The conversation also touches on the physical implications of using unrealistic scenarios, such as a current loop generating a magnetic field without external influence, and the necessity of specifying conditions at infinity for a well-defined solution. Ultimately, the dialogue underscores the mathematical nature of electromagnetic theory and the critical role of boundary conditions in solving related problems.
  • #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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