Basic misunderstanding of electric flow...

Joshik · Post by **Joshik** » 06 Dec 2009, 07:40

Hello! I have just completed my second pedal build (Bazz Fuss & Colorsound One Knob), so my competency status has been upgraded from "Complete Moron" to "Serious Dumbass". As I'm starting to learn more, I've run into a basic theory problem.

One of the basic rules of electronics is that the direction of current flows from the negative terminal of a battery to the positive terminal. Yet up to this point, I have been reading schematics/layouts from upper left to lower right and visualizing the power flowing from "9V+ in" to the negative ground. But if power flows from the neg terminal, then does the current enter through the battery to the instrument jack into the board, and up and out? Arrgh - what simple thing am I missing here? I'm sure it's intimately related to the ideas of "positive ground" and "negative ground" circuits, as well as the difference between NPN and PNP transistors...

Can someone explain this to me in a way that will light up the LED in my head? After passing through the 4.7K resistor of course. Or is that BEFORE passing through the 4.7K resistor...

Greg · Post by **Greg** » 06 Dec 2009, 09:03

Benjamin Franklin originally surmised that Electrons flowed from positive to negative.
When this was later shown to be wrong, it was decided to keep this convention as it was well established.

It's known as "conventional flow" as opposed to "electron flow" which is from negative to positive.

Knowing the direction of flow doesn't affect the circuit, but it can be confusing.

lolbou · Post by **lolbou** » 06 Dec 2009, 09:38

May I give a teacher's answer Greg?

Well, in fact, back in 1820, Hans-Christian Oersted shown that current through a wire had a specific direction, and could move a compass needle placed below the wire in one direction or another according to the current direction.

Ampere took these results and start the basics of electromagnetics, assuming that current was flowing from the + lug of the battery to the - lug, the well-known conventionnal direction...

But in 1897, Joseph Thomson discovers electrons in atoms. And these are later proved to be responsible for electric current. Damn, shall they re-print every book to correct every electrical theory of the 19th century (quite a lot) by adding a minus in front of every formula? Or shall they give an appropriate definition of what a bloody current is?

The second option was choosen. Now, a current is a flow of charge (in Coulombs) per second, no matter positive or negative ones.

They're negative in metals, but are both positive and negative in ionic solutions, human cells and nerves, etc.

Joshik wrote:Yet up to this point, I have been reading schematics/layouts from upper left to lower right and visualizing the power flowing from "9V+ in" to the negative ground. But if power flows from the neg terminal, then does the current enter through the battery to the instrument jack into the board, and up and out?

Don't forget electrons are both pushed by the 0V of the battery and attracted by the +9V of the battery. Therefore they travel the shortest way. They might travel along your instrument jack lug, but won't drive up to your guitar unless it is a 9V guitar...

Greg · Post by **Greg** » 06 Dec 2009, 10:22

lolbou wrote:May I give a teacher's answer Greg?

But of course.. mine was the quick and dirty version..

Yours is much better.

lolbou wrote: Ampere took these results and start the basics of electromagnetics, assuming that current was flowing from the + lug of the battery to the - lug, the well-known conventional direction...
...

So is the common story about Franklin wrong ?

"When Benjamin Franklin made his conjecture regarding the direction of charge flow (from the smooth wax to the rough wool), he set a precedent for electrical notation that exists to this day, despite the fact that we know electrons are the constituent units of charge, and that they are displaced from the wool to the wax -- not from the wax to the wool -- when those two substances are rubbed together. This is why electrons are said to have a negative charge: because Franklin assumed electric charge moved in the opposite direction that it actually does, and so objects he called "negative" (representing a deficiency of charge) actually have a surplus of electrons. "

lolbou · Post by **lolbou** » 06 Dec 2009, 10:48

Here's what Wikipedia says about this:

Wikipedia wrote:His discoveries included his investigations of electricity. Franklin proposed that "vitreous" and "resinous" electricity were not different types of "electrical fluid" (as electricity was called then), but the same electrical fluid under different pressures. He was the first to label them as positive and negative respectively

In here, "vitreous" refers to glass, and "resinous" to amber (in ancient greek = "elektron")... Franklin was studying static electricity, assuming the charges were fluids as said above... The + and - did not refer to an electric charge at the time (this was 50 years before the electromagnetic theory), but were just used to identify the two types. He could have called them ying and yang, or north and south...

But here's a very intersting line in this Wikipedia article about Franklin:

Wikipedia wrote:Franklin never patented his inventions; in his autobiography he wrote, "... as we enjoy great advantages from the inventions of others, we should be glad of an opportunity to serve others by any invention of ours; and this we should do freely and generously."

He did not invent goop, for sure...

Joshik · Post by **Joshik** » 06 Dec 2009, 16:34

Thanks, guys! This makes perfect sense.

Here's a nice link that shows a teacher highlighting the same confusion:

http://www.rare-earth-magnets.com/magne ... n_flow.htm

amptramp · Post by **amptramp** » 04 Jul 2011, 20:11

Just to confuse matters firther, electrons move from positive to negative inside a battery or generator. Fun stuff, this electronics, isn't it?

DrNomis · Post by **DrNomis** » 04 Jul 2011, 21:11

It doesn't really make a great deal of difference which convention you use, Electron Flow, or Conventional Current, when analysing how an electronic circuit operates, the only caveat is that you stick with one convention throughout the analysis....

I agree with Greg_G, Electrons were proved to be Negative in charge, and because of that Electrons are attracted to a positive charge as shown by this statement:

Like charges repel, un-like charges attract.

If you really want to understand electron flow in a circuit, we must go down to the atomic level, the type of electrical charge in a substance is determined by whether the substance has a deficit, or abundance of electrons, if a substance has a negative charge, it has an abundance of electrons in the valence shells around the atoms, if a substance has a positive charge it has a deficit of electrons in it's valence shell, an electrical current is caused by the electrons being knocked out of their positions in the valence shell, and the electrons moving to a position in the next atom's valence shell, sort of like "leap-frogging" at the atomic level, the thing that knocks the electrons out of their positions in the valence shell is Electrical Pressure (analogous to the water pressure in a water pipe), and a unit of this Electrical Pressure is called the "Volt" (named after Alessandro Volta (spelling?)), an electric current is therefore a flow of Electrons passing through any one point in an electric circuit, a unit of this current flow is called the Ampere (named after a French scientist).

Fender3D · Post by **Fender3D** » 04 Jul 2011, 23:04

DrNomis wrote:....
a unit of this current flow is called the Ampere (named after a French scientist).

hmm Ampierre maybe?

DrNomis · Post by **DrNomis** » 05 Jul 2011, 00:35

Fender3D wrote:
DrNomis wrote:....
a unit of this current flow is called the Ampere (named after a French scientist).

hmm Ampierre maybe?

Yeah....possibly, if you're going with the "correct" French spelling.....

Maybe Lolbou could clarify that for us....

Fender3D · Post by **Fender3D** » 05 Jul 2011, 23:44

DrNomis wrote: Yeah....possibly, if you're going with the "correct" French spelling.....

Maybe Lolbou could clarify that for us....

Oh well...
if they ate Volta's "A" they might as well eat Ampierre's "I"...

"R" was eaten by Frenchs already

DrNomis · Post by **DrNomis** » 06 Jul 2011, 01:06

Fender3D wrote:
DrNomis wrote: Yeah....possibly, if you're going with the "correct" French spelling.....

Maybe Lolbou could clarify that for us....
Oh well...
if they ate Volta's "A" they might as well eat Ampierre's "I"...

"R" was eaten by Frenchs already

And don't forget the "E's"....most important ingredient in the Ohm's Law equations.....

CharlyG · Post by **CharlyG** » 06 Jul 2011, 03:07

When the Navy taught me solid state theory, (I had begun with tube theory), we were taught that to explain these devices, we had to consider that the electrons themselves didn't move, but the places they were did? I really had issues with this! They called it hole theory at the time.

Seiche · Post by **Seiche** » 06 Jul 2011, 17:14

CharlyG wrote:When the Navy taught me solid state theory, (I had begun with tube theory), we were taught that to explain these devices, we had to consider that the electrons themselves didn't move, but the places they were did? I really had issues with this! They called it hole theory at the time.