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### Topic: Is this utterly wrong? (Read 4324 times)previous topic - next topic

#### DROBNJAK

##### Jan 06, 2013, 01:09 am
I've always imagined that electrons move in the circuit like a gas pulled by electric field. All that at some speed, which was significant, maybe like 30,000 mph. But at any rate a great speed. That is why we get heating up, because that electron gas keeps on colliding with atoms in the wire.

Now, I watched this video on YouTube: http://www.youtube.com/watch?v=jbi7gJTPSXk and the guy claims that electrons move at snail's pace.

Does electric current inside the wire move very fast or very slow (like that video claims)?

#### AWOL

#1
##### Jan 06, 2013, 01:26 am
Quote
Does electric current inside the wire move very fast or very slow (like that video claims)?

Electric current moves pretty fast, but, from memory, electrons move about three to ten metres a second.
Around walking pace.
(the analogy I remember from school is "imagine pushing peas into a long tube. The far-end pea moves out almost as soon as you shove in a pea, but the actual speed of an individual pea is low")

#### MAS3

#2
##### Jan 06, 2013, 01:34 am
Yep, you didn't get all that was told in your video.
It states that an electron moves slow, i don't think current was even mentioned (just electricity).
I have no idea how fast an electron moves, AWOL stated a speed just now.
But you need to keep track of what terms are used, to understand what is presented to you in movies like these.
Have a look at "blink without delay".
Did you connect the grounds ?
Je kunt hier ook in het Nederlands terecht: http://arduino.cc/forum/index.php/board,77.0.html

#### retrolefty

#3
##### Jan 06, 2013, 01:46 amLast Edit: Jan 06, 2013, 05:00 am by retrolefty Reason: 1
I think the key to understanding this is there is not a single string of electrons all in a line jumping from one atom to the next, rather the cross section of the wire represents a gazillion of atoms all jammed in parallel and series so any one specific electron just finds an adjacent nearby atom closer to the positive potential to jump to and some other electron then jumps to another atom and on and on. There are so many atoms all involved in allowing electron migration that any specific electron makes very slow progress down the wire.

Anyway it's the sear number of atoms available as carriers for the electron flow that the progress for any single specific atom to make it's way down the wire will be very slow going.

I believe the total amount of electrons flowing at any given current amount is what a Coulomb is about and one can see by the constant value that a whole lot of electrons are involved when current is flowing.

Quote
One coulomb is the magnitude (absolute value) of electrical charge in 6.24150965(16)×10e18 protons or electrons.[1]

Lefty

#### dhenry

#4
##### Jan 06, 2013, 02:05 am
Quote
Does electric current inside the wire move very fast or very slow (like that video claims)?

Electrons move relatively slowly.

Electronic magnetic field moves (propagates) very fast.

#### TroyO

#5
##### Jan 06, 2013, 04:57 am
Now that is interesting. Had no idea it worked that way. My mind was blown when I found out electrons flowed from negative to positive too.

#### oric_dan

#6
##### Jan 06, 2013, 05:01 am
Quote
Now that is interesting. Had no idea it worked that way. My mind was blown when I found out electrons flowed from negative to positive too.

The convention for current flow that we use for calculations, ie plus to minus, is just a
"convention", and was invented before it was known that electrons carry current, rather
than positive particles.

#### retrolefty

#7
##### Jan 06, 2013, 05:09 am

Now that is interesting. Had no idea it worked that way. My mind was blown when I found out electrons flowed from negative to positive too.

Yea there is classic battle fought for ages about what direction 'current' flows. In the military they taught us using electron flow being negative to positive, but the EE profession talks (as taught in colleges and universities) of current flowing from positive to negative.

I think it's just a legacy of the origins of the discovery of electronics where they knew current was following but couldn't directly observe it so they guessed and standardized on P to N. When later more knowledge of the basic atom and it's role in current flow they decided that rather then admitting their mistake, invented the concept of 'hole flow' to continue justifying saying that current flows P to N.

The only thing moving in the wire is electrons so I say current flows N to P, but that is a battle long ago fought to no satisfaction to either side. The problem is the EE world gets to define all the semiconductor arrows which now point in the wrong direction!

Lefty

#### WizenedEE

#8
##### Jan 06, 2013, 05:16 am

Yea there is classic battle fought for ages about what direction 'current' flows. In the military they taught us using electron flow being negative to positive, but the EE profession talks (as taught in colleges and universities) of current flowing from positive to negative.

When a line of traffic stopped at a stop light starts moving, each one is moving forward but the point at which one car is moving and another is not is moving backward. "Current" isn't electrons, it's the movement of electrons.

#### retrolefty

#9
##### Jan 06, 2013, 06:17 am

Yea there is classic battle fought for ages about what direction 'current' flows. In the military they taught us using electron flow being negative to positive, but the EE profession talks (as taught in colleges and universities) of current flowing from positive to negative.

When a line of traffic stopped at a stop light starts moving, each one is moving forward but the point at which one car is moving and another is not is moving backward. "Current" isn't electrons, it's the movement of electrons.

Typical EE response.

As I said 'they' invented 'hole flow' to justify their original failed guess. I say just follow the electrons, they know which way they are going.

Lefty

#### fungus

#10
##### Jan 06, 2013, 09:48 am
Obligatory xkcd:  https://xkcd.com/567/