Magnetic field lines around electron and wire seem to contradict

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SamRoss
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In the picture below, the direction of the magnetic field lines can be determined by using the right-hand rule with the thumb pointing in the direction of the current.
1604436073035.png


If we use the right hand rule in the picture below, thinking of the yellow arrow as the current, we would not get the correct direction for the magnetic field.
1604436057040.png


I'm aware that electrons do not literally spin around like little tops, but they are often depicted as spinning around because they have magnetic fields around them as if they were spinning. I'm curious as to why the electrons would be depicted as spinning around in a direction which would contradict the right-hand rule. Is it because their angular momentum is in this direction (that is, in a direction such that the relationship between it and the magnetic field can be found with a left-hand rule instead)?
 

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Nugatory
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What is the charge of the electron, and what is the convention for the direction of charge flow in an electric current?
 
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SamRoss
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What is the charge of the electron, and what is the convention for the direction of charge flow in an electric current?

I see. So in the first picture I posted, the current is pointing up but the electrons would actually be flowing down. Is that it?
 
  • #4
Nugatory
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https://xkcd.com/567/
Yes, the direction of positive current flow is opposite to the direction of electron movement.
(And in practice it is almost never helpful or necessary to think about an electric current in terms of moving electrons)
 
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PeroK
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I see. So in the first picture I posted, the current is pointing up but the electrons would actually be flowing down. Is that it?
You can blame it all on Benjamin Franklin apparently.
 
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vanhees71
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https://xkcd.com/567/
Yes, the direction of positive current flow is opposite to the direction of electron movement.
(And in practice it is almost never helpful or necessary to think about an electric current in terms of moving electrons)
The cartoon is great, but I tend to the opposite opinion concerning the statement. To the contrary I think it's always of great advantage to think about the motion of the conduction electrons relative to the positive ion lattice in a metal when it comes to currents in usual conductors. With this in mind there's almost no more trouble with Faraday's Law of induction in connection with problems like the homopolar generator or the correct relativistic treatment of the current-carrying wire:

https://www.physicsforums.com/insights/homopolar-generator-analytical-example/
https://www.physicsforums.com/insights/relativistic-treatment-of-the-dc-conducting-straight-wire/
 

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