Actually, the notion of "current flow" began when folks started
analyzing circuits and applying well-known circuit laws. To an engineer,
"current" is a mathematical entity and its use, etc. in a circuit model
has nothing whatever to do with the physics of how the actual
electrical current is being conveyed in the circuit through various
device and circuit elements. The circuit laws applying to currents,
voltages, etc. in the circuit do not concern themselves with the
physical mechanisms of current, per se or of the devices in the circuit.
Thus, when other folks - historically, the "technicians" - start looking
into circuits and analyzing and applying circuit laws, they are confused
by the seeming nonsense and inconsistency of the engineer's insistance
on using a current definition that has "current" flowing in a
vacuum-tube circuit such that it enters the anode (plate) and exits the
cathode! Since "everyone knows" that a vacuum tube operates on an
electron flow within the device, from cathode to anode, the engineer's
analysis seems totally in error and at odds with Nature. "THE LOGIC DOES
NOT WORK."
But, the key point is that the engineer DOES get the correct answers
when analyzing the circuit. And that is why to this day that formal
circuit analysis and modelling techniques assign the direction of
"conventional current" flow as being from + to - of the source of
electrical energy within a circuit. A positive voltage rise is the
voltage across a device from its negative terminal to its positive
terminal, polarities being taken in accordance with the assigned
direction of conventional current flow. All other circuit definitions
follow accordingly.
This is not a matter of sematics nor is it some sort of schoolboy battle
of wits between the "engineers" and the "technicians." It is a
fundamental aspect of circuit analysis that has served well for probably
the better part of 100 years now. It has survived from the earliest days
of electricity to the modern days of semiconductor devices. Just keep in
mind that "current" can be a mathematical entity having nothing to do
with actual physical mechanisms and nothing is lost in using it that
way.
Sorry if this turned into a sermon, but I would hate to see the list
cluttered up - one more time! - with a current-flow vs electron-flow
"discussion." Kinda like those "voltage decibels" that we hear about
from time to time. <:}
72/73, George W5YR - the Yellow Rose of Texas NETXQRP 6
Fairview, TX 30 mi NE Dallas in Collin county QRP-L 1373
Amateur Radio W5YR, in the 55th year and it just keeps getting better!
Icom IC-756 PRO #02121 (9/00) Kachina #91900556 (12/99) IC-765 (6/90)
Dan Cox wrote:
>
> hehe, it's really amazing that the myth ever got started. Supposedly it was
> easier around the turn of the century to explain electricity if you
> explained it in the reverse of how it actually works.. Imagine these
> people's confusion when they started learning about vacuum tubes for
> instance! The logic just DOES NOT work!!
--
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