Is electric current only a flow of charge?

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Discussion Overview

The discussion revolves around the nature of electric current, specifically questioning whether it is solely a flow of charge. Participants explore the concept of bound currents in magnetized materials and their implications for measuring current with a galvanometer.

Discussion Character

  • Conceptual clarification
  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants question the reality of bound surface currents in magnetized objects, particularly whether a galvanometer would show deflection when connected to such surfaces.
  • One participant suggests that if bound currents were real, there should be a measurable deflection on the galvanometer, but they express skepticism about this expectation.
  • Another participant argues that no deflection should be observed, as there is no continuous flow of charge along the surface of the magnet, referencing a text that describes surface currents as arising from tiny current-carrying loops rather than a flow of electrons.
  • Some participants agree that the concept of surface current may be more of a theoretical model rather than a physical reality, questioning the meaningfulness of experiments designed to test its existence.
  • One participant challenges the notion that electric current is defined only as a flow of charge, suggesting that this definition may be too restrictive.

Areas of Agreement / Disagreement

Participants generally express skepticism about the reality of bound surface currents and agree that a galvanometer would not show deflection. However, there is disagreement regarding the implications of this for the definition of electric current and the meaningfulness of experiments to test the reality of surface currents.

Contextual Notes

The discussion highlights limitations in understanding the nature of bound currents and their measurement, as well as the dependence on theoretical models versus physical reality. There are unresolved questions about the definitions and implications of electric current in this context.

shubham agn
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A magnetized object is always described as having bound volume and surface current. Are these bound currents real? I mean if I connect a galvanometer between two points on the surface of a magnetized iron sphere, will the galvanometer show a deflection?
If it does then it is very strange because Iron is magnetized because of the spin of its electrons which are point particles. So they can't really create a "flow" of charge along the surface to create a surface current. How then can we explain the "reality" of surface current?
 
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Let's suppose that the current were real. How much deflection would you expect to see on the galvanometer?
 
DaleSpam said:
Let's suppose that the current were real. How much deflection would you expect to see on the galvanometer?
I think no deflection should be seen as there is no charge that is flowing along the surface. In Griffiths text on Electromagnetism, the author has explained the surface current as being caused due to tiny current carrying loops whose current "touches" the surface. The cumulative effect of all such loops would be a surface current (although it is not due to continuous flow of charge). But in real materials there are no such tiny loops inside but electrons instead of them which are point particles. So now we evidently cannot explain the surface current. So in this case, the surface current is not there apparently and is just an imaginary physical model to describe the magnetization. Am I right here?
 
No deflection of no galvanometer. You're right.
 
shubham agn said:
I think no deflection should be seen as there is no charge that is flowing along the surface.
You are correct, no deflection should be seen. A galvanometer measures current through the galvanometer. The bound current is bound to the surface of the magnet, so it doesn't flow through the galvanometer.

My point is, if you want to decide if something is "real" then you have to figure some experiment that would be different if it were real or not. The galvanometer is not such an experiment because regardless of whether it is real or not it doesn't flow through the galvanometer and therefore you don't expect anything different.

I cannot think of any such experiment, so I don't think that the "is it real" question is scientifically meaningful.
 
Who sais that electric current is only flow if charge?
 

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