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

[atharba]

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?

 

[Ibix]

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.

 

[atharba]

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)?

 

[Ibix]

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.

 

[PeroK]

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.

 

[Dale]

Even with a constant drift speed there is still acceleration around a bend in a wire.

 

[PeroK]

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.

 

[Gavran]

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.

 

[Dale]

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.

 

[jbriggs444]

... 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.

 

[DaveE]

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?

 

[Gavran]

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?

 

[Dale]

Can you recommend something that can be found on the internet?

My favorite is "A semiquantitative treatment of surface charges in DC circuits" by R Mueller https://www.tu-braunschweig.de/inde...oken=2cc8a71e4fdbf159121c6b8ef8348952a2e0c197

The seminal paper on this topic is "Surface charges on circuit wires and resistors play three roles" by JD Jackson. https://pubs.aip.org/aapt/ajp/artic...t-wires-and-resistors?redirectedFrom=fulltext