# Electron flow

1. Jan 7, 2012

### nshamblin

What is the speed of electron flow in an eletric curcuit? A battery (cell) with a copper wire shorted across the positive and negative posts. What will the electron flow be through the copper wire?

2. Jan 7, 2012

3. Jan 7, 2012

### rollcast

Each individual electron moves very slowly for example in a copper wire of radius 1 mm carrying a steady current of 10 Amps, the drift velocity is only about 0.024 cm/sec.

However because there are electrons throughout the whole length of the copper wire, its a bit like pushing on the end of a pipe full of putty, the putty at the opposite end starts to move even though your end hasn't moved very far.

4. Jan 7, 2012

### nshamblin

does the speed change? or is it constant? for instance does the speed of I depend on its volume which would in turn be dependant on E or R ?

5. Jan 7, 2012

### rollcast

$I = nAvQ$

Where,

I = electric current
n= charged particles per unit volume
A= cross sectional area of conductor
v= drift velocity
Q= charge of each particle

so therefore

$v = \frac{I}{nAQ}$

6. Jan 7, 2012

### nshamblin

Thank you for your help. Ive been imersed in labor these past 40 years having to set aside some of the questions Ive had since childhood. I thank you for clearing this one up. My electronics instructor years ago said the electrons in a cucuit moved at the speed of light, which I always questioned, because of mass issues, Now I know. thanks again.

7. Jan 7, 2012

### rollcast

http://www.jimloy.com/physics/electric.htm [Broken]