# Current philisophy

Discussion in 'Electronic Basics' started by Rodney Kelp, Mar 31, 2005.

1. ### Rodney KelpGuest

So, are they still teaching hole flow in electronics schools or are they
back to electron flow?

2. ### John LarkinGuest

Current flows [1] from positive to negative. Engineering and physics
schools never taught anything else. The military and some trade
schools taught electron flow, and may still. That confuses the hell
out of the poor students.

"Hole flow" happens in semiconductors.

John

flows", of course.

3. ### Active8Guest

No. The terms are "pedants" and perhaps "pissy". And going back to
basic physics, we always talked about electrons accelerating in a
field and about charge per time. Since we were talking about the
charge of electrons, I always got the impression that we were
talking about negative to positive. The positive to negative
convention was introduced in electroncs.

4. ### Roger JohanssonGuest

They are still teaching positive charge flow (=current), and that is what

Forget about electron flow unless you have some special reason to
consider elementary particles movements or molecular chemistry in some
special cases.

5. ### John LarkinGuest

Nicely self-referential!
The positive to negative convention was introduced by Benjamin
Franklin a long time before electronics was invented or electrons were
discovered.

John

6. ### R.SpinksGuest

Hole flow is still taught in semiconductor classes.

7. ### MeGuest

For me in beginning physics, we talked about electric fields as pointing
from a positive charge to negative charge, so that a positive test
charge will feel a force pushing it towards the negative charge. This
morphs into positive charges flowing out the positive side of a battery,
the right rule giving you the right direction for the magnetic field set
up by that positive current, and so on. You could just as easily talk
about negative charges flowing the other way, and using a left hand rule
instead. That is if I say 6A is flowing from the right side of your
screen to the left, then that is either 6 A worth of positive charge is
flowing from right to left, 6 A worth of negative charge flows from left
to right. As the Circuits book I just finished they actually go to
great pains to establish that being consistent when working a problem is
the only thing that matters.

Hole flow is different, in that holes don't really flow in a
semi-conductor, right. That is given a positive type semi-conductor
there are holes in the atoms making up the material, and electrons hop
in and out of the holes, the atoms being fixed in place, so the
appearance is that holes are flowing the opposite way through the
material. I never really had a formal electronics class (I always liked
the AoE approach where you don't really care about the internals of the
devices, but just how to make them useful), so maybe I'm wrong.

Craig

8. ### Active8Guest

Moi? I just state it correctly. I don't think I get pissy about it,
but I might point it out.
Someone mentioned that here and/or in an article on lightning.

Let me rephrase that. The positive to negative convention was
introduced to *me* in electroncs ... *after* I learned that
electrons flow from neg to pos which was years before I took
physics.

9. ### Active8Guest

^^ Hey, Me. You're Me
Yup. My pre-physics knowlege of electronics probably caused me to
favor the opposite view - a negatice charge being attracted to the
positive charge. But remember, you don't need a negative charge for
a positive one to set up a field or exert a force on another
positive charge.
Yeah, but it doesn't hurt to talk pos to neg with others. That way
we're always on the same sheet.
Right. They don't *really* move. It's just an unoccupied electron
position. Holw flow is discussed as is their drift velocity. If you
want a bit of fun learning, check out "The Britney Spears Guide to
Semiconductor Physics." If you want the same thing on a paper plate,
try MIT's open courseware. 6.021 Microelectronic Devices and
Circuits
AoE serves its own purpose. The formal approach has it's own merits.
Ok. Me is Craig. How's that for ebonics?

10. ### PeteSGuest

As numerous others noted, both are taught. Although there are comments
about holes not really moving (each individual hole roughly stays put),
the conduction in P material actually effectively takes place in the
valence band, not the conduction band.

That's the reason P-channel devices are slower, incidentally (lower
energy level).

All of this is part of quantum mechanics (and to quote Niels Bohr, as
close as I can 'anyone not outraged on first hearing about quantum
mechanics did not understand what has been said').

Cheers
PeteS

11. ### John LarkinGuest

Oh, of course. You're the only one who matters.

John

12. ### John LarkinGuest

Except that Fluke won't sell you a negative-charge ammeter, and no
engineer is going to keep you on the payroll for long if you keep
getting the signs reversed.

John

13. ### Active8Guest

Ok. It was introduced to me, perhaps you, and most likely others at
some point in time after we started learning about electronics.