How does special relativity affect the Hall effect in conductors?

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Discussion Overview

The discussion explores the implications of special relativity on the Hall effect in conductors, particularly focusing on how relativistic speeds of charge carriers might alter the traditional calculations and understanding of the Hall voltage. The scope includes theoretical considerations and potential corrections to existing models.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant outlines the standard derivation of the Hall voltage and questions how to adjust this derivation for relativistic speeds of charge carriers, suggesting the use of relativistic momentum.
  • Another participant expresses uncertainty about the relevance of relativistic effects, noting that in typical metals, the velocity of charge carriers is much less than the speed of light, implying that relativistic corrections may not be necessary in conventional scenarios.
  • A later reply emphasizes that relativity applies at all speeds and suggests that magnetism can be explained through relativistic effects on moving charges, proposing that high-speed electrons in a vacuum could be treated as relativistic charge carriers.
  • One participant mentions that Maxwell's equations are fully relativistic and implies that the Hall effect may also be affected by these principles, although they admit limited knowledge about the quantum aspects involved.
  • Another participant reiterates that the velocities of charge carriers in metals are generally much lower than relativistic speeds, suggesting that this diminishes the need for relativistic considerations in the Hall effect.

Areas of Agreement / Disagreement

Participants express differing views on the necessity and relevance of relativistic corrections to the Hall effect. While some acknowledge the theoretical implications of relativity, others argue that in practical scenarios involving typical conductors, relativistic effects may not be significant.

Contextual Notes

There are limitations in the discussion regarding the assumptions made about the velocities of charge carriers and the conditions under which relativistic effects become relevant. The discussion does not resolve the mathematical implications of incorporating relativistic momentum into the Hall effect calculations.

cragar
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In the regular hall effect we calculate like this
F=qE=qvB then E=vB , now we assume our conductor has width d so we multiply both sides d.
then Ed=vBd=V so now our Hall voltage is vBd v is the speed of the charge carriers and B is the magnetic field. But what if our charge carriers were moving at relativistic speeds? How would we correct our derivation. Could I just write my initial velocity in terms of momentum p=mv and then use
relativistic momentum.
 
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I am not certain that I can answer your question but in the 'regular Hall effect' as you call it, the velocity of charge carriers is always going to be very much less than c.
In a metal carrying a current v is of the order of mm/s so there is no real problem in the 'regular hall effect'
 
cragar said:
In the regular hall effect we calculate like this
F=qE=qvB then E=vB , now we assume our conductor has width d so we multiply both sides d.
then Ed=vBd=V so now our Hall voltage is vBd v is the speed of the charge carriers and B is the magnetic field. But what if our charge carriers were moving at relativistic speeds? How would we correct our derivation. Could I just write my initial velocity in terms of momentum p=mv and then use
relativistic momentum.

Relativity applies at ALL speeds. The effects are not always obvious, at first glance but, for example, you can explain Magnetism in terms of the relativistic effects on the moving charges in any conductor and reduce it to a simple Electric force.
Extending your question: you could replace the charge carriers, moving in a solid, with high speed electrons in a vacuum and you would then be dealing with charge carriers that are, in fact, moving at high enough speeds to be regarded as 'relativistic', in the conventional sense. (Ha - relativistic and conventional in the same sentence.) You would be dealing with what's effectively, a high energy cyclotron situation - which is dealt with in many textbooks.
 
Maxwell's equations are fully relativistic. (Maxwell's equations are invariant under the Lorentz transform).

So the answer is probably yes, though I don't know a lot about the quantum end of things.
 

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