# Electron Motion

1. Sep 22, 2006

### Karthikeyan

Hi,
I believe that the free electrons in a piece of a conductor move randomnly until they are oriented in one particular direction by some external field. Does free electrons lose energy in this random motion??

2. Sep 22, 2006

### AbedeuS

All collisions between the delocalised electrons are completely elastic, meaning all kinetic energy they have is transferred to neighbouring electrons when they move close (due to magnetic repulsion), this process is 100% effective unlike day to day mechanical processes.

EDIT: I'm new here so my answer may not be right though

3. Sep 22, 2006

### Karthikeyan

Let me say, I've a free electron 'X' at energy level E1 wandering inside the conductor. When u say the energy is transferred, do u mean the electron 'X' will come down to a lower energy than E1??

4. Sep 22, 2006

### Karthikeyan

Conduction of electrons

Hi all,
Can anyone please give a brief explanation on movement of electrons in conductors?? How the force is transmitted from the voltage source..interms of what?? Photons???

5. Sep 22, 2006

### Astronuc

Staff Emeritus
Electrons 'flow'/'drift' with the local potential difference or electric field. It could be static (DC) or dynamic (AC) and it could be induced by a time varying magnetic field (induction).

6. Sep 22, 2006

### Karthikeyan

I mean how does the energy get transmitted from electric field?? Free electrons are already present in metals wandering here and there, right?? By applying some field the direction of motion is oriented. I am asking how this force orients the electrons?? Also, does free electrons lose any energy in their random motion in the absence of any external field??

7. Sep 22, 2006

### AbedeuS

A lower kinetic energy yeah, but try not to confuse it with electical charge (1.6*10^-19 C), electrons constantly move about the conductor freely, this is reffered to as "Delocalised" electrons, their kinetic energy or delocalisation is usually based off the temperature of the substance.

Now I'm pretty poo on the physics front but there is a way of finding out the energy, let somone better correct me but i believe the kinetic energy of the electron (average) is boltzman constant * temperature, i stress AVERAGE because some electrons can have alot of energy and some cant since it's pretty dynamic and repulsions between electrons happen pretty often.

For figureing out the "AVERAGE" speed of the electron i believe you can just use E = KT (average energy) and E=1/2*M*V^2 (reaarange this). But beats me :(

Last edited: Sep 22, 2006
8. Sep 22, 2006

### ZapperZ

Staff Emeritus
Maybe you should start with the simplest explanation of charge transport using the classical picture, which, from the tone of your question, is what you are asking for.

http://hyperphysics.phy-astr.gsu.edu/hbase/electric/ohmmic.html

Zz.

Edit: You have posted an almost-identical thread in two different forums. Please pay attention to the PF Guidelines that you have explicitly agreed to. Multiple posting is strictly not allowed. The two threads have been merged, and if the outcome makes no sense, it isn't my fault.

Last edited: Sep 22, 2006
9. Sep 22, 2006

### Staff: Mentor

This question was answered in post #2.