Direction of current flow

[silverstar84]

Forgive this intrusion of but I’m sure someone here on this forum has an answer I fail to find by Goggle.
I am preparing a technical speech and I want to share that Ben Franklin’s conjecture of current flowing from Positive to Negative was largely due to a lack of equipment with that ability.
My question, does anyone know WHEN was the flow of current from Negative to Positive discovered?
Thank you in advance.
Michael

 

[Sceadwian]

A few seconds on Google gave me this blurb in a thread. The quality of the links you get varies widley depending on the terminology you use.
Direction of current

Then in 1900, J.J. Thompson discovered an electron and proved electrons are negative and that they flow to a positive charge.

Obviously you'd want to do more research than a simple thread post on a forum, but that should be a good starting point. JJ Thompson is credited with this discovery but further digging may find older clues.

 

[silverstar84]

Thank you very much,
My search criteria was to long.
I was close to your search, but no cigar.
This will work
Thanks again.

 

[ke5frf]

Without Googling anything or specific dates or names, the idea of negative to positive flow roughly corresponds to the discovery of the semiconductor.

 

[Sceadwian]

Not true, because if you reverse the polarities of everything the devices still work just fine even if you don't know how they work fundamentally. The majority of the human race does not know that the positive terminal of a battery is actually the source of negative particles. Discovery of the semi conductor effect has absolutely nothing to do with the understanding of electron flow in a material. The effect was observed and experimented with before such understanding was developed.
Novel uses and understanding of complex semi conductor effects are to this day still being discovered.

 

[ke5frf]

All I know is my work library has dozens and dozens of electronics books dating late 1930s to the present, and the ones prior to the 1950s describe positive to negative electron flow...all with tube circuits, while the ones published during the 1950s and 60s state both models, suggesting that the (then) standard model of positive to negative was dated by solid state developments, while anything published past 1970 describes negative to positive flow as a foregone conclusion with no need to explore the alternative.

What I'm suggesting is that textbook theory was modified by the proliferation of solid state electronics, in the general public.

Not trying to be argumentative or debate when the first actual proposal to the contrary was made, BTW.

 

[MikeMl]

...
My question, does anyone know WHEN was the flow of current from Negative to Positive discovered?

The flow of "Current" is ALWAYS from Positive to Negative!!!

Electrons move from Negative to Positive.

So what are you asking? When were electrons discovered? or that electrons carry a negative charge?

 

[Sceadwian]

Mike, there are two different ways of looking at current. 'Conventional' current flows from positive to negative, while electron current flow is from negative to positive. If you ask a physicist which direction the current is flowing, they'll likely give you the opposite direction as compared to an electrical engineer. The Wikipedia entry on electric current under conventions explains it relatively clearly. It's a matter of perspective, reverse all the signs and it works the same either way. In a metallic conductor current flow is in fact from negative to positive. The lines become quiet blurry in semi conductors and more complex conductive substances.

 

[MikeMl]

Mike, there are two different ways of looking at current. 'Conventional' current flows from positive to negative, while electron current flow is from negative to positive. If you ask a physicist which direction the current is flowing, they'll likely give you the opposite direction as compared to an electrical engineer. The Wikipedia entry on electric current under conventions explains it relatively clearly. It's a matter of perspective, reverse all the signs and it works the same either way. In a metallic conductor current flow is in fact from negative to positive. The lines become quiet blurry in semi conductors and more complex conductive substances.

No! there is current , and there is movement of electons. The Wiki article is very specific on this:

"A flow of positive charge gives the same electric current as an opposite flow of negative charge. Thus, opposite flows of opposite charges contribute to a single electric current. For this reason, the polarity of the flowing charges can usually be ignored during measurements. All the flowing charges are assumed to have positive polarity, and this flow is called conventional current. Conventional current represents the net effect of the current flow, without regard to the sign of the charge of the objects carrying the current.

In solid metals such as wires, the positive charge carriers are immobile, and only the negatively charged electrons flow. Because the electron carries negative charge, the electron motion in a metal is in the direction opposite to that of conventional (or electric) current."

 

[Sceadwian]

That's only true in metals Mike, it gets a whole lot more complex in semi conductor materials, fluids, ionized gasses and chemical reactions.

 

[MikeMl]

Current is the effect; movement of electrons or movement of positive charge carriers is the cause . There is no such thing as "electron current", there is only "current". Read the Wiki discussion again (and again)....

Your statement that there are two different ways of looking at current is false. There is only one definition of current. Period! There happen to be two types of charge carriers that swim in opposite directions; so what!

 

[Sceadwian]

https://web.engr.oregonstate.edu/~traylor/ece112/lectures/elect_flow_vs_conv_I.pdf
It's not false the entire reason we use conventional current flow is a hold over from before we knew the electron even existed. What is flowing where is very important in semi conductor materials, chemical reactions, and fluid flows especially with ionized fluids/gasses What I find odd is that conventional flow managed to stick, even though it's exactly opposite of the actual polarity of the charge carriers involved.
The reason the electron should get the right of way so to speak with respect to current flow is while holes and electrons swap places in materials generally for electric charge to move but holes are not required, electrons are. Proof is as simple as the electron gun, where electrons can be blown out of an atom completely and sent to a remote location to do work. A hole can not. Conventional current has always rankled with me for that simple reason. Demonstrate a hole gun and I'll say it doesn't matter =)

 

[ajish_gopal]

conventionally the direction of current is taken from positive termainal to negative terminal. The flow of electron is always opposite in direction as compared to the direction of current.

 

[MikeMl]

...
The reason the electron should get the right of way so to speak with respect to current flow is while holes and electrons swap places in materials generally for electric charge to move but holes are not required, electrons are. Proof is as simple as the electron gun, where electrons can be blown out of an atom completely and sent to a remote location to do work. A hole can not. Conventional current has always rankled with me for that simple reason. Demonstrate a hole gun and I'll say it doesn't matter =)

I spent half my life at a microcircuit lab, including running an ion implant machine, which is basically a particle accelerator, where POSITIVELY charged ions are accelerated by a 25,000 to 100,000V electric field, focused by magnets, deflected by charged plates and then slammed into a semiconductor wafer to implant impurities into the silicon to dope it. The beam current is measured in uA, and consists entirely of positively charged particles moving in a vacuum. I'd say it is a hole gun.

 

[jamesinnewcastle]

If 'Current' was never defined as electron flow then its definition of 'something' flowing from positive to negative flow is correct - simply because a definition is exactly that, a definition. As Humpty Dumpty said "A word means what I choose it to mean, nothing more, nothing less'.

A yard is as long as it is because someone defined it as being that long. If you later define centimeters it doesn't change the length of a yard!

If you need to argue about definitions - try 'time' - That's a definition so ingrained that people believe it actually exists as some sort of entity whereas it is 'just' a definition! Interestingly it also means that any eminent scientist that argues that 'time' can be altertered in any way, or travelled through, is a Wombat - it's a definition!

James

 

[Sceadwian]

It's not though Mike, seeing as you have some actual experience in the matter as me who is just an armchair physicist you know this. In electronics regardless of what else is going on the electron is king =) That's why I don't like the idea of conventional current flow because it is always against electron current flow. The electron is what moves and does the work. Charged particles are a totally different story =)
Out of curiosity, what do they actually bombard the silicon with? I know (roughly obviously) how ion implantation works, but what do they use, striped semi conductor material, or something else?

 

[MikeMl]

...
Out of curiosity, what do they actually bombard the silicon with? I know (roughly obviously) how ion implantation works, but what do they use, striped semi conductor material, or something else?

Boron, Phosphorus or Arsenic ions. Each atom is turned into an ion by stripping an electron, and then the positively charged ion is accelerated by an electric field gradient, focused into a beam, and then the beam is scanned across the Si wafer. The wafer is mounted on an insulated (from ground) holder, which is wired to an op-amp current to voltage converter. The beam current (several tens of uA) is a measure of how many ions are hitting the wafer per unit time.

 

[Sceadwian]

That's amusing that they use an opamp (that very well may be been made using the same method) to provide current feedback. The atom choice makes sense, but how do the get that far? Do they used powdered materials and something like a vendegraph generator to strip the electrons off? I hear about this kind of stuff all the time, never seen any pictures let alone movies of the equipment and practical considerations that go into those types of process, personally it's incredibly fascinating to me.

 

[Coug]

Hi all,
A method of thinking I have practised may help you ??...
Put aside one moment all you have been taught about "current flow" and view this situation through a different scenario. Lets look at the simple capacitor. Consider this the "smart" battery that it is. When a capacitor, battery etc is receiving a charge, it "collects" a charge on BOTH plates, the negative "CHARGE" on one and the positive 'CHARGE" on the other. Due to the dialectric the charge doent flow through the capacitor but rather builds up on each plate until there is no more room, so to speak, on each plate. This is proof to the diode effect that developes as a capacitor becomes fully charged per given voltage. Pressure of the voltage . ie the higher the voltage the more pressure. OK - we all know and understand what I have just presented however lets substitute the charges and pressure for something tangible we also understand and similarise this to our "two" directions - types of "current and electron" flow.

If we liken "CHARGE" to people, and lets say that "positive" charges are men, while "negative" charges are women or visa versa, and we cram ALL THE MEN in one room and all the WOMEN in another room - each room being a plate taking the opposite charge. LAWS OF NATURE insist on finding an equilibrium. So now we must have an equal number of men and women in each room. What happens is men will exit their room, walk or run down the passage way to the room where the women are, passing the women who are heading over to the room where the men are leaving, "SAME PATHWAY, OPPOSITE GENDER, OPPOSITE DIRECTION" to find the equilibrium. Lets call their pathway "Current Flow" for the men and "Electron Flow" for the women. Same thing with electricty or "Electric CHARGES"

The measurable standard for "current" is a dirivative or net effect of the two passing influences, ie in a given pathway you may only be able to "fit" 4 people wide during travel - ie "resistance" to movement. Since everyone is travelling as fast as they can to get to their destination with respect to the "GIVEN RESISTANCE" we measure 4 people per branch of particular circuit - OR AMPS. Widening the passageway is like lowering the resistance for the equilibrium to take place quicker hence more people "CHARGE" per given space higher measure of volume ie AMPS.
Equilibrium completes and now no more amps, no flow, no more worry till another "pressure" forces things to move outa place again.
The most important thing to remember is that along the pathway the "negative" and "positive" charges WILL NOT amalgamate. They do not neutralise each other and wont mix, not naturally anyway. Maybe you will need the hole gun from MikeMI to make em mix
Hope this helps.

 

[mbarazeen]

current always flow from possitive to negetive, its defined as rate of flow of +ve charge dQ/dt. rate of flow of -ve charge is claled electron flow rate. when a sphere of +ve charge is discharged to ground via a conductor, we say charge flows from sphere to ground. in actual electrons flow from ground to the spare and neutralize it.