Drude Model: Electrons & Collisions

Click For Summary

Discussion Overview

The discussion revolves around the Drude model of electrical conduction, focusing on the behavior of electrons and their collisions. Participants explore the assumptions of the model, particularly regarding the randomization of electron velocities post-collision, and delve into related equations involving the Fermi sphere.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant expresses confusion about the assumption that electrons move in a random direction after collisions, questioning the likelihood of this assumption given the context of their velocities prior to collision.
  • Another participant references a previous post for additional context on the topic, suggesting that there may be more detailed explanations available.
  • A participant seeks clarification on an equation related to the displacement of a Fermi sphere, specifically questioning the role of δk and its interpretation in the context of steady-state motion.
  • Another reply suggests that δk likely represents a variation in k, but also advises the participant to post a new question for more focused attention.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the assumptions of the Drude model, particularly regarding the randomization of electron velocities after collisions. There are multiple viewpoints and ongoing questions about the interpretation of related equations.

Contextual Notes

There are unresolved assumptions regarding the behavior of electrons post-collision and the implications of the equations discussed, particularly in relation to the Fermi sphere and its motion.

aaaa202
Messages
1,144
Reaction score
2
As far as I understand: In the Drude model we take the electron to be moving in a random direction after each collision (*), such that the mean velocity is simply the average of -eEt/m, which is just -eEτ/m, where τ is the relaxation time.
But I am very confused about this basic assumption (*), if the electron has a velocity in the direction of the field and suffers collision with another electron, it does not seem likely that the direction of the velocity of the 2 electrons after collision will be completely random.
 
Physics news on Phys.org
That was quite helpful. Now I don't suppose you could help me interpreting another
l) states that the equation for the displacement of a Fermi sphere is (all h's are hbars):
h(d/dt + 1/τ)δk = F
Now Newtons law for a completely free electron is:
hdk/dt = F
Why have they put in a δk, and how is the equation to be interpreted? Does it represent the motion of the Fermi sphere in steady state?
 
Probably the variation of k ...

You would get more attention by posting a new question.
 

Similar threads

Graduate Relaxation time and average electron velocity in Drude model
  • · Replies 1 ·
Replies
1
Views
3K
Undergrad Mean speed of electrons in a periodic potential / lattice
  • · Replies 3 ·
Replies
3
Views
3K
Graduate Drude model relaxation time approximation
  • · Replies 2 ·
Replies
2
Views
3K
Undergrad Understanding dissipation of energy in a resistor through the Drude model
  • · Replies 1 ·
Replies
1
Views
2K
Undergrad Understanding Newton's 2nd Law & Drude Assumption for Conductivity
  • · Replies 1 ·
Replies
1
Views
3K
Undergrad Do electrons have a net motion when a DC voltage is applied?
  • · Replies 7 ·
Replies
7
Views
3K
Graduate Doubling I, what happens to v_d and n?
  • · Replies 2 ·
Replies
2
Views
2K
Undergrad Issues in understanding screening effects in the Jellium model
  • · Replies 0 ·
Replies
0
Views
3K
Graduate Ohm's Law derivation from Drude Model
  • · Replies 4 ·
Replies
4
Views
13K
Ambiguous question on momentum and how it works...
  • · Replies 13 ·
Replies
13
Views
1K