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Poll: electrons in wires

DrPizza

DrPizza

Administrator Elite Member Goat Whisperer
Inspired by the dumbest misconception you had as a child thread. Lets see how many of you actually know. When you flip a switch on the wall to turn on the lights, how fast do the electrons travel to the light?
 
IIRC, the individual electrons move relatively slowly ... though I'm not sure if the turtle would win. However the EM field propagates at (nearly?) the speed of light.
 
Electrons moving is a function of the conductor diameter and the current. But it's quite slow. It's been equated to a tube full of marbles, shove one in, and one pops out the other side instantly, the marble going in didn't move out instantly, but the effect was near instantaneous. Usually said to be the speed of light.
 
Well, electrons moving at or almost at1 the speed of light is winning by almost a 2 to 1 margin. I'll bet the physicists are glad their field isn't a democracy!
 
Originally posted by: DrPizza
Well, electrons moving at or almost at1 the speed of light is winning by almost a 2 to 1 margin. I'll bet the physicists are glad their field isn't a democracy!
Click to expand...
And everyone else is just glad that somebody cares enough to work in the field 😉
 
I'm not sure how fast but one time I sent my colleague down the hall an email before I walked over to him. I beat it by a few seconds. 😉
 
Aren't those of you speaking of a drift velocity also speaking of DC circuits?
How many of you have a switch on the wall that controls a DC circuit to turn on lights?
I always thought the drift velocity in an AC circuit was 0. In DC, it depends on the wire size, current, etc. (I may be wrong about the AC) But, the drift velocity in a wire is calculated by drift velocity = current divided by (neA) where n = free electron density of the material (for copper, about 8.5 x 10^28 electrons per cubic meter) and A = cross sectional area of the wire. In a 5 amp circuit with a 1mm diameter wire, the drift velocity is less than 3 cm per minute.
So, regardless of whether it's 3 cm per minute, or 0, a turtle still moves faster 🙂 (I considered a snail)
 
At this point, I am the only person who voted "instantaneously". Because, you know, I didn't know the answer and I decided to fail in the most spectacular way possible. 🙂
 
Originally posted by: Skoorb
I've not read any responses, so I am guessing a bit slower than the speed of light, but pretty close to it.
Click to expand...

Look at the wire at the atomic level and see what's going on compared to light -

light travels as photons in a straight direction

electrons travel on a wire by moving between valence shells, in more of a domino effect. Electrons are attracted to the potential on the other end until eventually they've exchanged themselves down the line. This is why heat is generated.

I'm hoping some day carbon nanotubes will be produced to shoot electrons in a straight path down them. Then we wouldn't have to worry about the conversion process between electronic and fiber optic media.
 
Boy: Do not try and move the electrons. That's impossible. Instead only try to realize the truth.

Neo: What truth?

Boy: There are no electrons.
 
Originally posted by: DrPizza
Aren't those of you speaking of a drift velocity also speaking of DC circuits?
How many of you have a switch on the wall that controls a DC circuit to turn on lights?
I always thought the drift velocity in an AC circuit was 0. In DC, it depends on the wire size, current, etc. (I may be wrong about the AC) But, the drift velocity in a wire is calculated by drift velocity = current divided by (neA) where n = free electron density of the material (for copper, about 8.5 x 10^28 electrons per cubic meter) and A = cross sectional area of the wire. In a 5 amp circuit with a 1mm diameter wire, the drift velocity is less than 3 cm per minute.
So, regardless of whether it's 3 cm per minute, or 0, a turtle still moves faster 🙂 (I considered a snail)
Click to expand...


Ah, but drift velocity is just net displacement over "large" periods of time, electrons are actually moving much faster than that due to the thermal energy in the environment but it is in a random pattern. Technically, electrons are moving about quite quickly at room temperature but this isn't really relevant to the question.

That 3 cm/minute net drift velocity figure sounds about right, from memory (btw, technically we're talking about speed here since we don't mesure/care about the electron's direction)
 
Lots of people are taught in HS that "electricity" moves at nearly the speed of light. I think there's just a lot of people who are confusing "electrons" with "electricity" and the two really aren't the same thing.

ZV
 
Electrons travel very slow. Less than mm per second. The actual electric field travel at the speed of light.
 
Oops, clicked the wrong thing in the poll.. too bad there's no takebacks. I'm assuming you're talking about drift velocity of the electrons right? Then it would be very slow.
 
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