Understand Vector Potential A Physically: Proof of E = ∂A/∂t - ∇φ

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Discussion Overview

The discussion revolves around the physical interpretation of the vector potential A in electromagnetism, particularly in relation to its connection with the electric field E and the magnetic field B. Participants explore the mathematical relationships and seek proofs for the equation E = ∂A/∂t - ∇φ, while expressing uncertainty about the physical significance of A.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants express difficulty in visualizing the physical meaning of the vector potential A, noting its mathematical relationship to the magnetic field B through the curl operation.
  • One participant mentions that their teacher suggested A does not have a significant physical interpretation, viewing it primarily as a mathematical construct.
  • Another participant agrees with this perspective, stating that the A-potential is introduced for symmetry in electromagnetic theory and plays a role as a gauge field.
  • There are suggestions to use Maxwell's Equations or integral forms to derive the relationship between E and A, indicating a desire for a mathematical proof.
  • One participant proposes a conceptual analogy, suggesting that A could be thought of as a field whose rate of rotation corresponds to the magnetic field and whose field velocity relates to the electric field.

Areas of Agreement / Disagreement

Participants generally express uncertainty about the physical significance of the vector potential A, with some agreeing that it is primarily a mathematical tool. However, there is no consensus on its interpretation or the implications of this perspective.

Contextual Notes

Participants reference the need for a proof of the relationship between E and A, indicating that they may lack access to comprehensive resources or textbooks that cover this topic in detail.

captain
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i am having trouble visualiszing what vector potential A means physically. I understand that if you take the curl of it it give you the magnetic field B. I was wondering if anybody could also direct me to a website or show me a proof of how the electric field E is equal to the partial derivative of A with respect to time minus the grad of the scalar potential. I have no clue where to find that proof and neither do i possesses a textbook that has the proof in it.
 
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captain said:
i am having trouble visualiszing what vector potential A means physically. I understand that if you take the curl of it it give you the magnetic field B. I was wondering if anybody could also direct me to a website or show me a proof of how the electric field E is equal to the partial derivative of A with respect to time minus the grad of the scalar potential. I have no clue where to find that proof and neither do i possesses a textbook that has the proof in it.

I still don't understand the physical significance of A. My teacher told me there wasn't really one... it was just a mathematical relationship. Anyway, it seems to be in the same direction the E field that gets induced by the B field (which may or may not be induced by an original field, E1)


how E = dA/dt:

use Maxwell's Equations, maybe the divergence theorem or one of those other integral forms... I'm having deja vu:

http://en.wikipedia.org/wiki/Maxwell's_equations
 
Pythagorean said:
I still don't understand the physical significance of A. My teacher told me there wasn't really one... it was just a mathematical relationship.
Your teacher is right on this one. The A-potential is introduced in the EM formalism to write the theory in a symmetrical way. It makes the step towards field theory more logic in the sense that the A field plays the role of the EM gauge field. Also, this potential is used to impose gauge-conditions to set the remaining degree of freedom that arises due to the definition of the A-field.

More here : http://en.wikipedia.org/wiki/Magnetic_potential

marlon

edit : you should also wonder about the question why they call the A field a POTENTIAL ! :wink: (hint : look at the definition of the scalar potential)
 
Last edited:
Pythagorean said:
I still don't understand the physical significance of A. My teacher told me there wasn't really one... it was just a mathematical relationship. Anyway, it seems to be in the same direction the E field that gets induced by the B field (which may or may not be induced by an original field, E1)


how E = dA/dt:

use Maxwell's Equations, maybe the divergence theorem or one of those other integral forms... I'm having deja vu:

http://en.wikipedia.org/wiki/Maxwell's_equations[/QUOTE]

so can i think of A as being a field who's rate of rotation equals the magnetic field and who's field velocity is equal to the electrical field.
 
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