Talk:Drude model

Lorentz extension to Drude?

As far as I know, The Drude-Lorentz model is called that because it is based on the Lorentz dipole oscillator model for electrons first published by Lorentz in 1878, with ω₀ = 0 due to the lack of interaction between the nuclei and conduction electrons. Unless there is some extension from 1905 that I am unaware of (in which case there should be a citation) — Preceding unsigned comment added by 129.11.70.31 (talk) 14:50, 26 August 2018 (UTC)

Frequency range?

So up to what frequency can this model satisfactorily explain things?--Light current 22:47, 30 March 2006 (UTC)

Added to article: at around 2 THz, electrical conductivity versus frequency no longer follows the smooth trend implied by the Drude model (citations in the article). Hfmi0dzjc9z8 (talk) 03:01, 14 June 2023 (UTC)

Inadequacies

Inadequacy is relative to purpose. If Drude explicitly removed terms from his model fundamental to explaining the Hall effect, the appropriate term would be limitation, not inadequacy. Dispersion (talk) 15:55, 13 July 2008 (UTC)

I changed the section title. Han-Kwang (t) 08:24, 14 July 2008 (UTC)

Graph

Would it be useful to include an indicative graph of real and im sigma vs log(frequency)? I could whip one up quickly, if folk thought it worthwhile. Grj23 (talk) 11:11, 31 August 2009 (UTC)

Well it can't hurt that's for sure.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 20:39, 31 August 2009 (UTC)

Okay, done. Let me know if you have any sensible feedback on it. I can be adjusted *relatively* easily... —Preceding unsigned comment added by Grj23 (talk • contribs) 06:54, 1 September 2009 (UTC)

Re(σ) and Im(σ) should be used instead of σ′ and σ′′ IMO. Also they should be both right aligned (for prettyness), if possible. Otherwise it looks good.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 17:59, 1 September 2009 (UTC)

Pronunciation

It would be great to include a line or two on the pronunciation of "Drude". McGraw-Hill's Encyclopedia of Science & Technology suggests [drüd], but many people, (at least here in the US), say [drüdə]. What is the correct pronunciation? Kaschev (talk) 15:45, 7 September 2009 (UTC)

Here's your pronounciation help. Drude was a German. Therefore: the e should be pronounced, but the emphasis is on the u. The u is to be pronounced as oo in 'good'. The e is to be pronounced as in 'the', not as in 'he'. Alex Vermeulen, Zoetermeer, The Netherlands Jordaan12 (talk) 12:55, 26 November 2009 (UTC).

I think you could go ahead and put that in. I personally like the (rhymes with prude) type approach, although perhaps IPA is better. Grj23 (talk) 04:46, 26 October 2009 (UTC)

In some physics courses, it can also be pronounced "Drudo" with emphasis on the u as in "good". — Preceding unsigned comment added by 2601:47:4002:6420:9C97:9F11:8899:8B7D (talk) 18:52, 29 November 2016 (UTC)

Complex Permittivity of Metals

Hi all. As part of my academic work, I have produced the wavelength dependent permittivity and refractive index for quite a lot of metals produced using different models (Drude, Lorentz-Drude, Brendel-Bormann). I thought it would be useful to include somewhere here. Any suggestions on the best place for the data, and the appropriate format to plot it in (HTML5, static images, table, etc.)? Drnathanfurious (talk) 12:23, 18 September 2012 (UTC)

Wrong by a factor two?

It seems to me that the page considers the velocity/momentum of the electron just before scattering rather than the time-averaged velocity/momentum, and as a result states a conductivity which is a factor two too high. Can anyone confirm this? Or could I be making the same conceptual error that Drude supposedly made in his original paper? 2noob2banoob (talk) 11:56, 29 April 2013 (UTC)

Can you provide some citations/references? Drnathanfurious (talk) 08:28, 30 April 2013 (UTC)

I cannot provide any references other than my intuitive understanding of the subject, which is why I asked whether anyone can confirm it or I am wrong, and didn't edit the article. Also, I've now seen the expression in the wikipedia article also in some other places now (don't remember exactly where) so I'm probably wrong. Still puzzled as to why I'm wrong though. 2noob2banoob (talk) 13:15, 2 May 2013 (UTC)

Nevermind I figured it out. It turns out that I had a wrong (or actually not so much wrong but non-customary) idea of the physical meaning of τ. I thought of τ as the average time an electron travels between collisions, but it is customary to define τ as the time the time the average electron (which is not necessarily about to collide) has travelled since it's last collision. Now that the premise of this this talk section turned out to be wrong and this talk section no longer serve a purpose, should I delete it or leave it here? 2noob2banoob (talk) 20:53, 2 May 2013 (UTC)

It's likely someone will have the same question in the future, so you should leave your answer for them. Drnathanfurious (talk) 08:22, 3 May 2013 (UTC)

Yes, thanks for posting this question, I was also confused about this. I think that in the first sentence under 'Explanations', 'τ' should be changed to '2τ' because we are defining τ to be the average time since the last collision, which is half of the average time between collisions. Ericlar (talk) 18:00, 28 April 2014 (UTC)

Thanks from me too for posting this question and the answer, because I was confused about this! I definitely think we should keep this question. (10:27 5 May 2015 (UTC)) — Preceding unsigned comment added by 78.134.84.195 (talk)

I'm the same anonymous user of the paragraph before. I changed the page to explain the concept better. (10:31 5 May 2015 (UTC)) — Preceding unsigned comment added by 78.134.84.195 (talk)

The article is still confusing because it still refers to τ as mean collision time in places, and doesn't sufficiently explain the importance of using the relaxation time τ versus the collision time 2τ. It seems to be a common mistake in other sources I've seen to call τ the mean collision time (see the various PDFs resulting from a google search about the drude model), and we should ideally point out and explain that common mistake. I don't have time right now, maybe later. Wicklet (talk) 00:09, 6 September 2015 (UTC)

Actually, in a Poisson process like the scattering described here, the average time since the last collision, the average time until the next collision, and the average time between collisions are all equal. It is counterintuitive, but mathematically rigorous. Feynman discusses this in his lecture on diffusion.

Jmkinder1 (talk) 06:16, 4 February 2021 (UTC)

References

"the mean time an electron has traveled since the last collision, not the average time between collisions"

"the mean time an electron has traveled since the last collision, not the average time between collisions"

Who wrote this nonsense? "mean time an electron has traveled since the last collision" is literally another way of saying the average time between collisions.

"mean time a car traveled since the last stop sign" is literally "the average time between stop signs".

Both refer to the span of time, on average, between any two stops/collisions.

--64.121.146.209 (talk) 16:59, 23 November 2017 (UTC)

I totally agree, I'll make the edition unless someone has anything against it. MaoGo (talk) 22:03, 25 November 2017 (UTC)

I believe that here, average time between collisions means "the average time interval between one collision and the next one", while "mean time since last collision" means "the average amount of time since last collision at a randomly chosen point of a particle's trajectory". A particle could have just collided, be about to collide or any point inbetween. The average time will be half the previous value by symmetry. — Preceding unsigned comment added by 189.49.249.75 (talk) 19:41, 28 November 2018 (UTC)

Error vs. Limitation

"Historically, the Drude formula was first derived in an incorrect way, namely by assuming that the charge carriers form a classical ideal gas."

This is misleading. The article suggests that Drude made a mistake when deriving his model. However, within the confines of his assumptions he did everything correctly. In science it is not "incorrect" to introduce simplifications and approximations.

This point was essentially already made in the section "Inadequacies". This is a limitation of his model, not an error.

131.111.5.158 (talk) 15:31, 6 March 2019 (UTC)

Sure. Any proposals? --MaoGo (talk) 15:36, 6 March 2019 (UTC)

References

@Flyredeagle: I saw that you are updating the article, that's great! Could please add some references for the history section (and elsewhere if possible)?--ReyHahn (talk) 12:41, 4 July 2020 (UTC)

I added some references is this enough to remove the note ?

AC field - sign in denominator

The article states that for AC field the formula is:

$\sigma (\omega )={\frac {\sigma _{0}}{1-i\omega \tau }}$

while using the convention:

$E(t)=\Re \left(E_{0}e^{i\omega t}\right);$

The article then explicitly states that using the other convention $E(t)=\Re \left(E_{0}e^{-i\omega t}\right)$ yelds a plus sign in the denominator ($\sigma (\omega )=\sigma _{0}/(1+i\omega \tau )$). Aschroft and Mermin however are using the convention $E(t)=\Re \left(E_{0}e^{-i\omega t}\right)$ and arrive to the same formula as in the article ($\sigma (\omega )=\sigma _{0}/(1-i\omega \tau )$). How is this possible?

— Preceding unsigned comment added by 217.30.64.102 (talk) 06:38, 13 April 2022 (UTC)