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I was told that Ohm's Law of resistance is wrong?

  1. Nov 9, 2004 #1
    Is that true?

    Becuase like my prof said that the resistivity of an object according to ohms law has nothing to do with certain factors when in reality it does such as current and electric field (i think)

    What is this field of QM called? Is it Quantum Electrodynamics?

    Can you suggest textbooks or books that would be a good read ?

    Note : i'm only in the second year of university - but i'd like to start this sometime!
     
  2. jcsd
  3. Nov 9, 2004 #2

    ZapperZ

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    Read this thread...

    https://www.physicsforums.com/showthread.php?t=51204

    Zz.
     
  4. Nov 9, 2004 #3
    So then the correction for Ohm's law is given by Drude's Law??
     
  5. Nov 9, 2004 #4

    ZapperZ

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    No, the Drude model is the derivation of Ohm's law... But the Drude model is an over-simplication of the description of conduction electron, where these electron are thought to be "free" electron gas.

    You may want to consider reading a solid state physics text if you are that keen on knowing this. I didn't recommend this before because you're only ..... what.... in your 2nd year?

    Zz.
     
  6. Nov 10, 2004 #5

    dextercioby

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    In the second year he should have serious trouble looking into transport phenomena in solids.As this chapter of solid state physics deals with Boltzmann equation applied to movement of free (electric) charge carries in a crystal,he should be knowing many things,like non-equilibrium statistical physics (kinetic/Boltzmann's equation approach) and fundamentals of solid state physics...I trhink that's too much to ask to a second year student.In my country,solid state is taught in the 3rd year.In parallel with QM and SP.
     
  7. Nov 10, 2004 #6

    ZapperZ

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    I don't think one needs to get into the Boltzmann transport equation to understand the Drude model. That is usually the first thing one sees in the very first chapter of, let's say, Ashcroft and Mermin text. I'm not saying he can understand even the Drude model with just a 2nd year education.

    However, to understand why even the Drude model itself isn't entirely correct would certainly require understanding the Boltzmann equation and more QM than one has at that level. Interestingly enough, the Boltzmann transport equation itself is highly classical (or maybe even just semi-classical). One needs to go to the Kubo model to get to the QM version of the transport problem. This is fine and dandy, except that the Kubo model is a pain-in-the-ass to solve. This is why the Boltzmann equation is still what we fall back on to very often.

    Zz.
     
  8. Nov 10, 2004 #7

    dextercioby

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    It's pretty intuitive,yes,you're right.

    Perhaps.Anyway,he should know better what he does know and what he doesn't.


    Let's not get into technical terms here.There's a huge distance from Drude to Kubo.


    Yes it's the Boltzmann's equation that gives you the 2nd principle in Clausius formulation,but it's the CLASICAL theory of linear responses developed by Kubo which justifies the linear thermodynamics of irreversible processes developed by Onsager in 1931.So far,i haven't seen any relevant application of the QM version of Kubo's theory,or maybe i haven't read enough on the subject.That should be it...
    :tongue2:
     
  9. Nov 10, 2004 #8

    dextercioby

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    I got another question on the validity of using Boltzmann'e equation wrt to solid-state physics...I'll post in a separate thread.
     
  10. Nov 10, 2004 #9

    ZapperZ

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    It has been a while since I dealt with this, and someone else (Dr. Transport?) can correct me if I'm wrong, but I think Mahan dealt with the Kubo model in his Many-Particle Physics text. And unless I am mistaken, the Kondo effect is one of the phenomena that can be explained starting with the Kubo formulation. The spin-flip between the conducting electron and the magnetic background cannot be included using Boltzmann transport equation.

    Zz.
     
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