Reference direction of electrical current in teaching/books

So, fix it!

Cheers! Rich

I never learned that electrons are positive, and I didn't have any trouble understanding how tubes work.

So, do you flip the sign on all the test equipment you use, or does the Air Force buy special backwards-reading meters and scopes?

John

Which is why the college boys make more money, and tell the techies what to do.

John

Now you're just being snotty.

Thanks, Rich

No, seriously, if you believe that positive current is the direction that electrons move, how do you interpret the current reading of a Fluke DVM? Do you mentally flip the sign it displays?

And do military schematics draw diodes the opposite way that everybody else does?

What about the Right Hand Rule?

John

Heavens, no! I'm astute enough to recognize that even though it's electrons that flow from negative to positive it's not a dramatic intuitive leap to realize that the results are functionally indistinguishable.

Sure! Works fine, for positive charge flow, or hole flow. Admittedly, for electron flow it's the Left-Hand Rule, but the effects are indistinguishable.

The difference, I guess, is that the college boys are insulated from reality by the ivied halls of academia, and us techs do the actual work. >:->

Thanks, Rich

Actually it's not necessary to flip anything and I think you know that John. They simply teach that electrons enter the negative terminal of a passive element. For diodes, electrons enter the "negative" side of a diode and so on... Current meters are interprted as the quantity of electrons flowing into the negative terminal of the meter.

The positive charge view is an arbitrary convention that dates from the time of Ben Franklin. Negative charge flow is equally valid in every way although it is certainly less intuitive if you try to understand things from an energy point of view.

Every engineering text I have clearly refers to the fact that positive charge flow is a convention. Some of the texts are quite old. Are you saying none of your books explain "conventional" current flow?

All the physics and ee books that I have say that an electron has a negative charge, and that current flows from positive to negative.

I've worked with a few military and Heald graduates who kept getting confused about current directions and diodes and transistors, so whatever they taught them wasn't helpful in the real world.

John

I can't imagine that it can be hard for some people to remember that conventional current flows from positive to negative, while the electrons flow from negative to positive to balance it out. ;-)

I guess my point is, IT DOESN't MAKE ANY DIFFERENCE! As long as you're consistent.

One thing that does confuse me - which end of a battery is tha anode? The end the positive charge comes out of?

Cheers! Rich

Positive charges don't come out of a battery ;)

Electrons leave via the anode (marked with a "-") and enter via the cathode (marked with a "+").

No, the end it flows into (thus it's the opposite terminal whilst recharging)

Not unless you connect the terminals with a liquid or a semiconductor or a photoconductor or an ionized gas.

A quick google search is about equally divided on the polarity of the anode.

I like the voltage convention, where "anode" is always the more positive terminal. But it doesn't much matter.

John

A nucleus isn't a hole. It is full of real positive charges, known as "protons."

Photoconductors do have holes; the protons don't move much. In ioninic liquids and ionized gasses, the positive charges - protons - do in fact move from the positive terminalo to the negative.

It's sort of useless to have terms that change meaning many times a second. Using the "current" standard, when a battery is delivering current, its pos terminal is the cathode, but when it's being charged it's the anode. That can change 120 times a second. Even more fun is a PV diode, where the diode anode is the cathode when it's generating power.

Which is why actual electrical engineers seldom use the words "anode" and "cathode" unless they are referring to a diode or a vacuum tube, and I've never heard an engineer switch the names of the diode ends when it operated in zener or PV mode.

I always call the p-doped side of a diode "anode."

Do you call the banded end of a diode "anode" when it's zenering but "cathode" when it's forward conducting?

John

Although in semiconductors, apparently, due to some quantum reason that I don't fully understand, the holes really do behave as though they were positively charged particles.

The difference shows up in the Hall effect, where positive charges moving one way are *not* equivalent to negative charges moving the other way. The Hall voltage generated by a p-type semiconductor is what you expect from moving positive charges.

If anyone can provide an intuitive explanation of that, I'd be most interested...

Hydrogen? Hydrogen is a major charge carrier in lots of situations. Situations that keep you alive.

Not precisely true, since you're in one of your bitchy moods.

The "whole atom" includes all the electrons, and a positive ion is missing some. A hydrogen ion *is* a naked proton.

I never claimed to be a typist. And just how much mobility do you think I documented, that you think they have less of?

Maybe you need a drink. You're sure in a bad mood.

John

And apparently the conductivity of ice is due to the motion of protons rather than electrons:

From that page:

"Proton conduction in ice and H-bonded materials is analogous to electron conduction in semiconductors."

I wonder if you could make a transistor out of ice...