3 ms·
Electrons in a copper wire do not travel at the speed of electricity. Not even close. Electricity travels at nearly the speed of light. Electrons themselves t
by Stratoscope 6y ago
Electrons in a copper wire do not travel at the speed of electricity. Not even close.
Electricity travels at nearly the speed of light.
Electrons themselves travel like molasses:
"In the case of a 12 gauge copper wire carrying 10 amperes of current (typical of home wiring), the individual electrons only move about 0.02 cm per sec or 1.2 inches per minute (in science this is called the drift velocity of the electrons.). If this is the situation in nature, why do the lights come on so quickly [when you flip the switch]? At this speed it would take the electrons hours to get to the lights."
This completely caught me by surprise, but it makes sense once it's pointed out. Imagine a pipe filled with solid balls that just fit in it, with little friction. If you push a ball in one end, a ball pops out the other almost immediately. But not the same ball! Even if you keep pushing balls in, that first one you pushed will take a while to get the other end.
Update: as rrobukef notes in a reply, this would be the case for direct current (DC). With the usual household alternating current (AC), the electrons barely move at all!
https://www.uu.edu/dept/physics/scienceguys/2001Nov.cfm https://www.uu.edu/dept/physics/scienceguys/2001Nov.cfm
https://wtamu.edu/~cbaird/sq/2014/02/19/what-is-the-speed-of-electricity/ https://wtamu.edu/~cbaird/sq/2014/02/19/what-is-the-speed-of...
- spurgu 6y agoActually, 0.02 cm * 60 seconds = 1.2 cm (not inches).
- rrobukef 6y agoFor AC, they move back as well. Thus electrons move less than 4µm from their original place (excluding Brownian movement, I assume)
- quickthrower2 6y agoAnother mindblower: you can chuck a capacitor at the other end and you’ve got a circuit with one wire! Hence you can get shocks from one live wire.
- WrtCdEvrydy 6y agoYeah, Physics 2 blew my mind with things like this. The electrons actually move mostly side to side as they bump into each other. Pushing power just pushes the ones further down the pipe into the light, not the ones entering the copper cable.
- vidanay 6y agoHole Flow Theory is weird. https://www.allaboutcircuits.com/textbook/semiconductors/chpt-2/electrons-and-holes/ https://www.allaboutcircuits.com/textbook/semiconductors/chp...
- b0sk 6y agoA ripple in a pool simply displaces the ball up and down vertically. The ball doesn't move along the wave
- Chris2048 6y agoMovement of charge is more like wave in water than flow of water. Also, the current tends to travel on the outside (skin) of the conductor.
- mrfusion 6y agoNow what if a wire was moving backwards in the opposite direction faster than the drift velocity? Could current still flow?