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Re: Holes and the Hall effect



On Thu, 21 May 1998, Leigh Palmer wrote:

Hugh Logan, in discussing the merit of calling the moving charges in
metallic conduction "holes" asks (after much uncontentious stuff):

<snip>
Another
related misconception is that the electron which emerges from
one end of a wire carrying a current is not the same electron
as the one that goes in at the other end, delayed only by
lightspeed. There is no way to tell any electron from any
other electron, and in a sense the statement is meaningless.
I never have understood why these factoids are inserted into
curricula.

I hope you weren't referring to my battery example. I was only trying to
explain in simplistic technician language what the direction of electron
current in the external circuit of a battery would be if the charge sign
convention were reversed.

If we teach that "charge flows in conductors", and use a classical model
for the charges, then we are not teaching a misconception. After all, it
really does work this way for high-mass charged particles, e.g. in ionic
conductors such as people, dirt, battery electrolyte, etc.

But if we teach beginning students that "electrons flow in metal wires",
then the strange QM behavior of electrons becomes an issue. And
non-metallic conductors then seems unnatural, since they are not like
wires.

While it may be a misconception that electrons in metals behave like
classical charges, isn't it a bigger misconception if students believe
that "flowing charge" ALWAYS equates with "flowing electrons"? If
students think that metallic conduction is the fundamental model, then
generalized conduction will be confusing. It should be the opposite:
electrons ARE weird and non-classical, they SHOULD be initially
confusing.


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