Direction of current flow

[Edd]

There are a lot of misconceptions in this thread, I'll try to clear a few things up:

Charge carriers can be positive or negative. In almost all electronics, these will be electrons in solid metal wires and semiconductors. They flow from high negative potential to low negative potential (ie. negative to positive).

In chemistry, you come across redox reactions. In liquid aqueous solutions, there will be positive ions which flow from positive to negative - the opposite direction to electrons. A simple example would be saltwater, where Na+ flows one way, while Cl- flows the other.

The reason we still use conventional current is because the idea of positive charges wasn't entirely incorrect - you can have positive charges (eg ions in solution). That, and the fact that all schematic symbols were drawn in the conventional current direction - diodes, NPN/PNP transistors, etc. The important thing is that polarity is defined and kept consistent. As long as you connect + to + and - to -, the actual current direction is irrelevant.

A battery or a capacitor doesn't store charges, nor do they store electrons. They store ENERGY. The misnomer comes from the two meanings of the word charge - yes they are "charged" with energy, but you do not fill them up with charges (eg electrons or positive ions). The net amount of electrons in a battery or capacitor is the same whether charged or discharged. (Here's a good explanation/analogy of capacitors.)

The majority of the human race does not know that the positive terminal of a battery is actually the source of negative particles.

???

That's because it isn't true.

A battery is comprised of 2 metals/substances - one that naturally oxidises, while the other naturally reduces. The oxidising substance loses electrons, while the reducing substance gains electrons. The substance which loses electrons becomes the negative terminal. These electrons flow out through an external circuit and back through into the positive terminal, reducing the other substance.

The Voltaic Pile is probably the simplest to understand. Zinc corrodes (oxidises) more readily than copper, so it will become the negative terminal, giving off electrons, which travel through a circuit and back to the copper, which reduces as it receives electrons.


Edit: Something else that might help you visualise what "conventional current" is in solid wires and semiconductors:
Imagine a group of people standing in a circle, where everyone has a ball, except one person. Each person passes their ball clockwise. However, the "hole", ie. the person who doesn't have a ball will appear to move anticlockwise. The balls are your electrons, and the absence of an electron is your conventional current flow. This is the principle of "hole charge carriers" in semiconductors.

 

[Vizier87]

Long posts for such a short question. Cool.

 

[Edd]

"What is the meaning of life?" is a pretty short question, yet the answer took tens of thousands of years until someone said it was 42.

 

[Sceadwian]

Sorry Edd, got my terminology backwards (again) this is a common thing for me to do =)

By the way, it took seven and a half million years. Took 10 million to come up with the question, and bugger it all the blew it up before they got it. Typical governmental botch up =)

 

[Coug]

A battery or a capacitor doesn't store charges, nor do they store electrons. They store ENERGY. The misnomer comes from the two meanings of the word charge - yes they are "charged" with energy, but you do not fill them up with charges (eg electrons or positive ions). The net amount of electrons in a battery or capacitor is the same whether charged or discharged. (Here's a good explanation/analogy of capacitors.)

Sorry to side track from the direction of current flow subject but hey...

Thanks Edd for the link - the explanation of how a capacitor works would help many to understand its workings, however nothing flows "THROUGH" a capacitor because of its dielectric. The Dielectric becomes strained under the pressure and will of course breakdown or allow flow through - but only after it has been damaged by too much "Pressure" ie Voltage. Take a close look at the illistration Number two, the "highly watered capacitor". While everything else about how this example cap works is correct, the diaphram "WONT LET" water pass through. It will stretch and strain but still blocks water passing. It is only alowing "Pressure- ie Voltage to increase mass on one side and decrease mass on the other.- volume being the same. It is pressure which causes unequal equilibrium. Everything in our universe works on this very law.

 

[Edd]

Yeah, I think it's a pretty good analogy. It really helps when you look into things like LC/RC/RLC circuits and visualise the diaphragm springing back to push water out the other way. I (at the risk of further derailing this thread), actually came across it after googling for transistor info and reading his article on How Transistors REALLY work - also relevant while we are on the topic of current flow and various misconceptions.

 

[kinarfi]

Here we go again, commonly referred to conventional vs electron flow,

 

[Coug]

Thanks Edd, Again another great link Great reading!!

That actually parallels to MY belief also about current flow. Whilst my explanation above was intended to clarify somewhat the "traditional" way of thinking, what I really believe is this ...
same as your above link but explained abit different using dominoes.

Watch an assembly "track" of dominoes fall and you almost have it. The first dominoe is pushed with a "force" external to its position, as it falls, moves, or "reacts" for a better usage of words, it imparts its energy, as a result of the applied force, onto the next adjacent dominoe and so on. So the dominoes dont actually FLOW they react and impart that energy to the next one. Oh My do I dare say.... Current flow is actually then - energy flow and amps is the measurement of energy transfer ???

When working with high power rare earth elements, this becomes more appearent.

Food for thought - if you make a track of dominoes split at an intersection you now have two tracks running same speed independant of each other transfering same energy in each track. Another split in each and so on. Keep this up and then have them ALL meet at the same spot at the same time - Whala Accumulation of energy which far surpasses the original imput ???

Sorry to take you off the course of which way does it go !!

 

[Coug]

Good one Edd you got me into reading more stuff while I was on that link !!
Thanks Mate - Oh well at least others may also be interested in this one from the same site.

Regard it as an appology gift from me (oh and Edd to the rest of you for side tracking this forum - sorry Edd had to include you !!

http://amasci.com/amateur/elecdir.html

 

[Sceadwian]

Lol that's some funny stuff. I posted the same link to "How transistors really work" twice in this forum in threads about how semi conductors work, unfortunatly they were generally arguementative threads about different semi conductor devices being voltage vs current vs charge controlled, when the reality is they're really all of those things, even though the materials only switch state do the presence of the electric fields.. It's a really good read and written well for the laymen with enough technical information to help people on what to search for next.

 

[Externet]

By definition, 6.24 × 10^18 electrons passing a given point each second constitutes one ampere, the unit of electrical current, and the electrons flow from positive to negative inside a battery; and from negative to positive outside a battery.
The definition of Ampere as electrical current unit does not consider 'positrons' nor 'holes' nor positive charges. It is electrons moving, with negative charge.

If some day, someone decided to create a conventional or not direction for current, it is his problem and of his followers.

The true electron flow direction from negative to positive was first found from early cathode ray tubes, and the shadow an obstacle in their path showed on a phosphor target.

 

[Edd]

Yes, most of that is correct, except unfortunately Thompson didn't discover the electron until after everything was defined as conventional current.

1 ampere = 1 coulomb per second. Remember though, inside a battery you will have movement of positive ions as well. Net current in amperes will be the difference of the respective positive ion and negative electron flow rates.

 

[Sceadwian]

No it's not Externet, look the definition up again, it's a bout electric charge which is not directly applicable to electrons only. I don't have a 'background' in chemistry, but I've had to deal with it, and ionic particle flow transfers PLENTY of charge without electrons having to move from one atom to another. No electron needs to be transferred for an Ampere to flow, it would be HIGHLY unusual if such a thing did a occur without electron flow though =) The numbers are in it's favor.


[edit]
What edd said.

 

[Coug]

Agreed Sceadwian,
You are right ! - " NO electron needs to be transfered for Amprere to Flow" - react but not flow. It is reactive movement, influence under pressure. Reacting to a change in "EQUILIBRIUM" or trying to balance it.

Let me share---
I am going to totally reject conventional thinking biefly and give another example.
My guess is, part the reason we progess rapidly in aquiring "new" technologies is because of the very fact that there have and still are people who dare to challenge the conventional ways.

Disregard MATHS and what we ALL have been told or taught, and consider this for a sec.

Rare earth -ie Neodynium will try and attract to itself electrons. I dont know why or how, it just does. However it doesn't take them just "tries" to take em - applies a force or "pressure" on them. The scarey thing here is - and I say this without proof, is that I wonder if a large, like humungously LARGE big neo could really upset things...
Anyway back to my theory - Neos have a tremendously large electron spin hence their powerful nature. They can move electrons, hmm now we cant measure the current but we can measure their force.

Electrons are moving violently yet no measureable AMPs unless the neo itself moves. Faradays magnet disc experiment - homopolar disc gives a small insight into this feature.
Sometimes conventional thinking needs to be placed aside in liu of things we see and discover through nature or different awareness

For anyone who "might" be interested
Faraday paradox - Wikipedia, the free encyclopedia

Disregard the maths and enjoy the reading
Maybe I should really start a new post? I fear that I have unintentionally taken this one off course. My appologies if this is the case.