When electric current passes through a copper wire, it gets heated, this is the famous Joule effect. The explanation for this is given as follows: Free electrons in the copper wire move very fast and "collide" with each other, thereby generating heat.

But we know that electrons are quantum objects. According to quantum mechanics they are neither particles nor waves.

How do we explain the Joule heating effect according to quantum mechanics? What we call "Joule heat" must be an exceedingly large amount of photons (coming out of the surface of the copper wire) of infra-red radiation due to accelerations of copper electrons. Am I correct?

  • $\begingroup$ Why can't quantum mechanical objects collide with stuff? (I mean what do you think the Large Hardon Collider does?) $\endgroup$ Jun 1, 2017 at 12:20
  • $\begingroup$ The electrons are not colliding with each other, they are colliding with ions in the metal. Notice that this only happen if the metal is not a prefect crystal (i.e. it must have defects) $\endgroup$
    – valerio
    Jun 1, 2017 at 12:25
  • $\begingroup$ Related: physics.stackexchange.com/questions/154242/… $\endgroup$
    – valerio
    Jun 1, 2017 at 12:26
  • $\begingroup$ Since solid state physics is based on quantum mechanics, I would have to say that Joule heating is handled just fine with carrier scattering and phonons. $\endgroup$
    – Jon Custer
    Jun 1, 2017 at 12:49
  • $\begingroup$ @JonCuster: Some people argue that phonons are just mathematical devices. Some argue that phonons are real things. What do you say ? $\endgroup$
    – atom
    Jun 5, 2017 at 3:25


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