[Amps] Electron HOLE flow

[Roger (K8RI)]

On 8/28/2013 6:36 PM, Fuqua, Bill L wrote:
>    In a workshop I teach, I explain to young students how current flows thru conductors.
> I put them all in a circle and insert myself into the circle. Then I tell them that they are the
> atoms that make up the conductor and I am a battery, I give each a shinny new penny with
> a negative sign on both sides. I then tell them that the pennies are free electrons and being
> the battery my job is to take them in one hand and hand them out on the other. So I take one penny
> into my positive hand from the first student, and telll him that now he is positive and must take one from
> his neighbor. This continues until the student on my negative side is short an electron (penny) and I
> give that student another penny.

In an introductory course we had to figure out the average speed of the 
electron drift in a #10 wire carrying 1 Amp.
Like the pool ball experiment the one entered and the other popped out 
almost instantly, but the average speed was somewhat faster than a fast 
walk IIRC.  It's quite possible that the original electron never did 
make it to the other end.

Although it was a fairly easy exercise, I don't remember the steps, 
other than all atoms were considered to have a free electron.  The 
number of electrons in a coulomb, and Avogadro's  number for atoms in a 
mole of copper.

Anyone remember how to do that?

73

Roger (K8RI)
>     While doing this one day, we started going faster and faster until something went wrong.
> A boy had two pennies and the girl next to him had none. I said, now we have a problem, remember, these are
> young elementary students. I told the boy that now he is negative, and the girl is positive. One kid pointed
> out that they must be attracted to one another. The boy and girl both said "yuck".
>
> 73
> Bill wa4lav
>
> ________________________________________
> From: Amps [amps-bounces at contesting.com] on behalf of Fuqua, Bill L [wlfuqu00 at uky.edu]
> Sent: Wednesday, August 28, 2013 6:23 PM
> To: Roger (K8RI); amps at contesting.com
> Subject: Re: [Amps] Electron HOLE flow
>
> sometimes I fell like Ben, given a 50-50 chance I always get it wrong.
> Bill
> ________________________________________
> From: Amps [amps-bounces at contesting.com] on behalf of Roger (K8RI) [k8ri at rogerhalstead.com]
> Sent: Wednesday, August 28, 2013 5:56 PM
> To: amps at contesting.com
> Subject: Re: [Amps] Electron HOLE flow
>
> On 8/28/2013 2:05 PM, Mike Waters wrote:
>> Absolutely it is an illusion. IIRC, that was erroneously introduced into
>> textbooks around 1970 the same time as the "electricity flows from positive
>> to negative" nonsense. Whoever came up with the latter never heard of
>> electron flow in a vacuum tube, among other things.
> You are quite right. The vacuum tube hadn't been invented yet when + to
> - (conventional current) was defined although you're a bit off on the
> date.  EEs have used conventional current since there have been EEs and
> it was defined by Ben Franklin.
>
> 73
>
> Roger (K8RI)
>> 73, Mike
>> www.w0btu.com
>>
>> On Wed, 28 Aug 2013 03:54:29 -0400, K8RI wrote:
>>>> They still refer to "hole flow" in introductory semiconductors.
>>> REPLY:
>>>
>>> "Hole flow" is an illusion, much like the moving lights on a theater
>>> marquee. If it helps to understand things fine, but holes don't move. It's
>>> more accurate to say a hole is created in one atom and disappears in
>>> another. For a brief time while the electron is in motion, there are
>>> actually two holes.  Neither one "moves".
>>>
>>> 73, Bill W6WRT
>>>
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