What causes potential difference in the conductor?

AI Thread Summary
The discussion centers on the causes of potential difference in conductors, particularly regarding the relationship between changing magnetic flux and induced electromotive force (EMF). Participants clarify that a changing magnetic field generates an electric field, as described by Faraday's Law, which is essential for creating potential difference. The conversation touches on the behavior of free electrons in conductors, noting that while they may align with the electric field, they do not move unless a current is induced. Questions arise about the quantum physics explanation of these phenomena, emphasizing the interplay between electric and magnetic fields. Overall, the discussion highlights the foundational principles of electromagnetism and their implications for understanding potential difference in conductors.
George_Tailor
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What cause potential difference in the conductor? I mean why the changing magnetic flux induce EMF? I understand the basics but I can't understand it. What I know: there is free electrons on the surface of a copper conductor. Electron have electric field vector and magnetic field vector and these are perpendicular. Electric vector point to the protons/core usually but these are delocalized electrons. In a changing magnetic flux these electrons always turn to the opposite side of flux with their magnetic vector but don't move. That's all, just turn. Why build it EMF? Where is the potential difference?
 
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Hello George! Welcome to PF! :smile:
George_Tailor said:
…there is free electrons on the surface of a copper conductor. Electron have electric field vector and magnetic field vector and …

No, you are treating "a changing magnetic flux" as if that is all there is.

You cannot have a changing magnetic field without an electric field …

Faraday's Law (one of Maxwell's equations) says ∂B/∂t = -curlE …

it's that E which cause the electric potential difference! :wink:​
 
tiny-tim said:
Hello George! Welcome to PF! :smile:


No, you are treating "a changing magnetic flux" as if that is all there is.

You cannot have a changing magnetic field without an electric field …

Faraday's Law (one of Maxwell's equations) says ∂B/∂t = -curlE …

it's that E which cause the electric potential difference! :wink:​


OK, I know the equation and all what you say. But what is the quantum physics explanation of this EMF? You mean if the magnetic field sort electrons in the same direction the electric field vectors of these also will point in one direction and this cause EMF? But why these electrons start to move in a short circuit?
 
George_Tailor said:
You mean if the magnetic field sort electrons in the same direction the electric field vectors of these also will point in one direction and this cause EMF?

Sorry, George, but I don't know what you mean. :confused:

A changing magnetic flux includes an electric field.

That electric field (obviously) affects the electrons, and it induces a current in a conductor.
 

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