Is there traction force between moving electrons & copper wire?

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Discussion Overview

The discussion revolves around the concept of traction force between moving electrons and copper wire in the context of electric current. Participants explore whether a similar force exists as in mechanical systems, such as walking on a road, and consider implications for current flow and forces in conductive materials.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants suggest that there may be a traction-like force between electrons and the copper wire, drawing analogies to mechanical systems.
  • One participant posits that if a million DC amps are flowing, a recoil force could be sensed by the conducting wire.
  • Another participant argues against the existence of a net recoil force, stating that any force exerted would cancel out in a closed loop circuit.
  • A participant introduces an analogy of a mouse running on a ring track to illustrate the concept of forces in a closed circuit, questioning the cancellation of forces.
  • There is a suggestion that while there might be a small force during changes in current, in steady state, the forces from collisions and scattering events would balance out.
  • One participant mentions that the force felt by electrons is related to the resistance of the metal and the reaction force felt by the atomic structure of the conductor.
  • Another participant critiques the use of the term "traction," explaining that the forces on electrons and nuclei in a wire are equal and opposite, and that electrons eventually arrange themselves to negate net forces.

Areas of Agreement / Disagreement

Participants express differing views on the existence and implications of traction forces between electrons and the wire. No consensus is reached, with multiple competing perspectives remaining throughout the discussion.

Contextual Notes

Participants highlight various assumptions about the behavior of electrons in conductors, the nature of forces in closed circuits, and the role of resistance, but these aspects remain unresolved.

cairoliu
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Common sense: walking on road, there is traction between shoes & earth.
I'm wondering: same thing for electric current's electrons & copper wire?
 
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If it's true, then if million DC amps flowing, then there may be recoil back force sensed by conducting wire.
 
I don't think so, and even if there is the force is going to be exerted all along a closed loop, so the recoil would cancel out to zero net force.
 
Drakkith said:
I don't think so, and even if there is the force is going to be exerted all along a closed loop, so the recoil would cancel out to zero net force.
Imaging a mouse running in-cage ring track.

fun-for-the-whole-family.gif


The recoil force spins the wheel of ring track, no cancellation of recoil to zero?

The ring track is analog to a closed circuit.

The running mouse seems to be always around bottom of cage, because the ring track is light very much, so little the friction on axle, in comparison to mouse weight.

If customizing a bigger friction ring track, it's possible to see mouse climbing near the top of cage.

In nuclear physics experiment, there is a so-called Theta Pinch, which carries millions amps, but unfortunately the 2 terminals are fastened to base frame; if not, I guess the copper coil may be seen spin? Not sure anyway.
 
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cairoliu said:
he recoil force spins the wheel of ring track, no cancellation of recoil to zero?

The ring track is analog to a closed circuit.
Ah, I see what you mean. I didn't take possible rotation into account. There might be a small force as the current ramps up and as it ramps down, but in the steady state there won't be a net force, as the force from the collisions and scattering events between the electrons and the ions would cancel out the accelerating force on the electrons.

Perhaps an isolated circuit might temporarily spin itself around slowly if floating in a vacuum, like a small motor turning a larger ring could do. I'm honestly not sure.
 
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I think the force you mention is caused by the resistance of the metal. Electrons are not entirely free to move in a metal but require small force to do so. When we apply an EMF across the ends of a conductor, the electrons feel a force in one direction and the atoms feel a force in the other direction. However, the atoms are locked into the metallic structure and cannot move. The force felt by the atoms may be considered to be the reaction force.
The definition of Newton's action and reaction is just a matter of which is the desired force.
 
"Traction" is probably not the word you want.

If I apply an electric field to a wire, the electrons feel a force F in one direction, and the nuclei a force -F in the same direction. (Also, the electrons eventually arrange themselves so that there is no force on either)
 

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