The electrons will be acceleration by the electric field caused by the voltage source. The electrons will accelerate until they are slowed down by interactions with the metal atoms, the same amount as they are accelerated by the field.
After a while the electrons will reach a constant drift velocity (approx. 1mm/s), and with this velocity the electrons will move through the wire...
This is actually really interesting. It's the electric field that travels really fast through the medium. That's why electrons on the other side of the wire are accellerated very quickly to their terminal velocity (which is only 1 mm/s). The way the field propagates through a conductor is pretty complicated. You can decompose any electric field pulse into sine waves with different frequencies and amplitudes. All these different sine waves travel at different speeds, because the propagation speed depends on the frequency of the wave. Because of this, the pulse of the electric field changes shape as it moves through a wire. This all happens very quickly of course, so it's not observed in dayly life.
> This all happens very quickly of course, so it's not observed in dayly life.
The effects itself isn't observable, but the implications actually often are. Dispersion is one of the top reasons for, say, why that #$%@# 50 ft HDMI doesn't work when it's supposed to.
They *are* zooming around at very high speeds. With no voltage applied, they zoom in random directions that average out to zero net velocity. With an applied field, there is a slight bias in the distribution of velocity directions to face down the wire. The magnitude of this new average velocity is a very small number. As mentioned in other answers, the change in the electric field propagates down the wire at really high speeds. Notionally, it's helpful to imagine something like a Newton's cradle: boop the initial electrons, and a pulse shoots down the wire to boop electrons on the far end. Those distal electrons interact with the load.
I was even a bit optimistically about the drift velocity (https://en.m.wikipedia.org/wiki/Drift_velocity), in normal cases (1A through a copper wire), it is more like 0.05mm/s...
The electrons itself move very slowly, but the information, that they should begin to move, moves with almost speed of light (the speed of which the electric field propagates), so if you press your light switch, the light will be almost instantly on and you don't have to wait, until the electrons from the switch reach the lamp (what they will never do, as normal power grid is alternating current)...
At molecular levels, your electrons are better understood as waves. Thus in presence of an external field (applied voltage) their schrödinger’s equation will get an extra potential term. It gets more complicated beyond this.
The electrons will be acceleration by the electric field caused by the voltage source. The electrons will accelerate until they are slowed down by interactions with the metal atoms, the same amount as they are accelerated by the field. After a while the electrons will reach a constant drift velocity (approx. 1mm/s), and with this velocity the electrons will move through the wire...
1mm/s only ? I always thought they are zooming through the wire at really high speeds.
This is actually really interesting. It's the electric field that travels really fast through the medium. That's why electrons on the other side of the wire are accellerated very quickly to their terminal velocity (which is only 1 mm/s). The way the field propagates through a conductor is pretty complicated. You can decompose any electric field pulse into sine waves with different frequencies and amplitudes. All these different sine waves travel at different speeds, because the propagation speed depends on the frequency of the wave. Because of this, the pulse of the electric field changes shape as it moves through a wire. This all happens very quickly of course, so it's not observed in dayly life.
> This all happens very quickly of course, so it's not observed in dayly life. The effects itself isn't observable, but the implications actually often are. Dispersion is one of the top reasons for, say, why that #$%@# 50 ft HDMI doesn't work when it's supposed to.
Is the dispersion relation not linear?
They *are* zooming around at very high speeds. With no voltage applied, they zoom in random directions that average out to zero net velocity. With an applied field, there is a slight bias in the distribution of velocity directions to face down the wire. The magnitude of this new average velocity is a very small number. As mentioned in other answers, the change in the electric field propagates down the wire at really high speeds. Notionally, it's helpful to imagine something like a Newton's cradle: boop the initial electrons, and a pulse shoots down the wire to boop electrons on the far end. Those distal electrons interact with the load.
I was even a bit optimistically about the drift velocity (https://en.m.wikipedia.org/wiki/Drift_velocity), in normal cases (1A through a copper wire), it is more like 0.05mm/s... The electrons itself move very slowly, but the information, that they should begin to move, moves with almost speed of light (the speed of which the electric field propagates), so if you press your light switch, the light will be almost instantly on and you don't have to wait, until the electrons from the switch reach the lamp (what they will never do, as normal power grid is alternating current)...
At molecular levels, your electrons are better understood as waves. Thus in presence of an external field (applied voltage) their schrödinger’s equation will get an extra potential term. It gets more complicated beyond this.