Why is the net acceleration of an electron in a conductor zero?

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Discussion Overview

The discussion revolves around the question of why the net acceleration of an electron in a conductor is considered to be zero. Participants explore various aspects of electron behavior in conductive materials, including drift velocity, acceleration, and the effects of electric and magnetic fields, with a focus on theoretical and conceptual implications.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • Some participants suggest that the net acceleration is zero due to collisions in all directions, implying that forces cancel each other out.
  • Others argue that when current flows, electrons must accelerate, as the drift velocity is non-zero, contradicting the idea of zero acceleration.
  • There is a claim that the average drift velocity can be considered constant in a steady current, leading to the assumption of zero acceleration.
  • Some participants clarify that while drift velocity may be constant in certain scenarios, it is not universally applicable, and acceleration can occur when current is initiated.
  • It is noted that even with constant drift speed, there can be acceleration due to changes in direction, such as around bends in a wire.
  • Participants mention the influence of magnetic fields and electric fields produced by surface charges on the wire as factors affecting electron behavior.
  • Philosophical considerations are raised about the nature of acceleration over time, suggesting that net acceleration is rare in observed phenomena.
  • References to literature on surface charges in DC circuits are provided, indicating ongoing research and discussion in the field.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the reasons behind the net acceleration of electrons in conductors. Multiple competing views remain, particularly regarding the conditions under which acceleration occurs and the implications of drift velocity.

Contextual Notes

Limitations in the discussion include varying assumptions about drift velocity, the dependence on specific scenarios, and the complexities of modeling electron behavior in classical versus quantum frameworks.

atharba
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Is it because due to all the collisions in every direction, there's always a force that is opposite to another force? Hence acceleration is zero?
 
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Turn your room light off. No current is flowing in the wire and the electron drift velocity is zero. Turn it on and the electrin drift velocity will be a few millimeters per second. The electrons must have accelerated.

Perhaps you had a specific situation in mind? Because the statement you asked about isn't generally true.
 
Ibix said:
Turn your room light off. No current is flowing in the wire and the electron drift velocity is zero. Turn it on and the electrin drift velocity will be a few millimeters per second. The electrons must have accelerated.

Perhaps you had a specific situation in mind? Because the statement you asked about isn't generally true.
Isn't the average drift velocity of an electron a constant value? Hence, shouldn't its acceleration be zero (since velocity is constant)?
 
atharba said:
Isn't the average drift velocity of an electron a constant value? Hence, shouldn't its acceleration be zero (since velocity is constant)?
As I pointed out in post #2, the drift velocity is zero when there is no current and non-zero when there is current. So the electrons must accelerate when the current is turned on, and no, the drift velocity is clearly not a constant value.

The drift velocity is a constant value if you are considering, for example, a steady current. It isn't in general. That's why I asked if you were thinking of a particular scenario.
 
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atharba said:
Isn't the average drift velocity of an electron a constant value? Hence, shouldn't its acceleration be zero (since velocity is constant)?
In a crude model where the electrons are drifting through the wire at a constant speed, then (clearly) there is no acceleration. Why would that be a question?

That said, classical EM tends to treat a current as a continous flow of charge. To model the electrons themselves would need QM (Quantum Mechanics). And that's a different ball game.
 
Even with a constant drift speed there is still acceleration around a bend in a wire.
 
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Dale said:
Even with a constant drift speed there is still acceleration around a bend in a wire.
... and in one complete circuit of the wire, the total acceleration is zero.
 
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Dale said:
Even with a constant drift speed there is still acceleration around a bend in a wire.
Due to the magnetic field produced by the current in the wire.
 
Gavran said:
Due to the magnetic field produced by the current in the wire.
Typically due to the electric field produced by the surface charges on the wire. There is a pretty decent amount of literature on this topic.
 
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  • #10
PeroK said:
... and in one complete circuit of the wire, the total acceleration is zero.
Unless, perhaps, one is monitoring charge carriers circulating in the evacuated tubes of a particle accelerator.

Admittedly, for a decent accelerator, the velocity change can be quite small while the momentum change is significant.
 
  • #11
On the slightly philosophical side, it's rare for anything to have net acceleration if you watch it long enough. Things that start tend to stop somewhere, eventually, or maybe return to a previous state like a planet in orbit. IDK, maybe a solar wind particle that makes it into deep space?
 
  • #12
Dale said:
Typically due to the electric field produced by the surface charges on the wire. There is a pretty decent amount of literature on this topic.
Can you recommend something that can be found on the internet?
 
  • #13
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