Help! Conventional Flow Vs Electron Flow

[Mikebits]

You mean holes can't flow in a vacuum? If electrons can flow in a vacuum why can't those new fangled holes also.

Lefty

**broken link removed**

 

[Sceadwian]

Hole's aren't discrete particles, they're electrons missing from the shell of an atom. It's like darkness, it's not real, it's just the absence of light =) Unless you're a kid, in which case the dark is very real!

 

[MrAl]

Hello again,


I just wanted to make the point that one really needs to know BOTH
ways of looking at it, because you never know which book you may
pick up in the future that uses one or the other, and if it uses the
'other' and you havent studied that way, you'll be almost lost with
that book.

 

[crutschow]

The weird part is that the engineering types, not wanting to admit that their original definition of current flow direction was wrong, went and invented 'hole flow' theory to somehow justify the original error. Sad part is that the engineering types get to define the arrow direction used in drawing semiconductor symbols so that's why all the arrows point backwards to true electron current flow.

Lefty

Hole flow is not just some weird invention to avoid admitting to the original error in defining current flow, it is a valid concept that is particularly used in describing the flow of charges in semiconductors (see Semiconductor - Wikipedia, the free encyclopedia). Holes are mathematically described as charge carriers in semiconductors and appear to have a higher mass and lower mobility then electrons. The reason PNP bipolar and P-Channel MOSFETS are slower then NPN and N-Channel devices and have higher on-resistance is because the P devices use holes as the majority charge carriers with their lower mobility.

 

[Sceadwian]

It doesn't matter how mathematically correct their conceptualizations are.
It is important to know that 'holes' do not in fact exist, they are the ABSENCE of an electron not a discrete particle themselves, and can not themselves travel anywhere, they are potential states, not carriers in a strict sense.

 

[q5101997]

Current goes from plus to minus. When a current flows through a resistor from top to bottom, the top is posative. Current flows from anode to cathode in a diode, base to emmiter in an NPN transistor. My university taught me bazar mathematics but I never analyzed a circuit using electron flow convention.

 

[crutschow]

It doesn't matter how mathematically correct their conceptualizations are.
It is important to know that 'holes' do not in fact exist, they are the ABSENCE of an electron not a discrete particle themselves, and can not themselves travel anywhere, they are potential states, not carriers in a strict sense.

Does a hole in the ground not exist because it's the absence of dirt?

 

[Sceadwian]

Q5101997 You're dead wrong. "Conventional current" flows from + to minus, but as has been said at least a dozen times so far the electrons themselves move from - to +

 

[q5101997]

I analyse circuits while I conceptualise "something" flowing from plus to minus. When I start dealing with AC LCR circuits every step of every mathematical equation assumes conventional current flow. I almost always get the right answer, and most of my circuits work. If one wants to think in terms of electron flow, become a particle physisist. An electron exists as a particle and a wave at the same time, and only upon observation does it randomly choose either state.

 

[birdman0_o]

Does a hole in the ground not exist because it's the absence of dirt?

While this statement is correct, it does not apply to electrons. Atoms have empty orbitals which are not physical "holes" when an electron or more is missing, it is more of a lack of charge density. Electrons do not stay in one place, they move around the atom in these high density locations, known as orbitals. When there is no dirt there is air, when there is no electron there is nothing (well, as far as we know for now).

 

[dknguyen]

While this statement is correct, it does not apply to electrons. Atoms have empty orbitals which are not physical "holes" when an electron or more is missing, it is more of a lack of charge density. Electrons do not stay in one place, they move around the atom in these high density locations, known as orbitals. When there is no dirt there is air, when there is no electron there is nothing (well, as far as we know for now).

THe absence of an electron alone is not enough for a hole to exist. Otherwise a hole would have zero charge. A proton from the nucleus that no longer has it's positive charged nulled because the electron has moved on is required. The electron is "the dirt" filling the hole in the ground, while the proton is "the ground". So there isn't nothing, there's a positive charge being generated by the proton. In a sense, the hole in an atom exists more than a hole in the ground.

 

[electric_n00b]

Thanks guys, I've read every post and they're very helpful. I've spent years not being able to clear this up in my mind till now!

The polarities are still correct. Electrons (- charge) flow from the - terminal of the battery through the circuit to + terminal of the battery.
Direction of Current
Electron Flow

When we say "current flows from + to -", we do NOT mean electron flow. We mean conventional current flow or "hole" flow. Do you know the concept of electrons and holes? We know positive charges come from protons and negative charges come from electrons. But we also know that protons do not flow since the proton is stuck in the nucleus, therefore positive charges do not physically flow. Electrons on the other hand, do flow since they can jump from atom to atom so negative charges can flow. But when the negative charge jumps, it leaves behind a "hole" of positive charge that originates from the proton in the nucleus which no longer has it's charge cancelled to zero because the electrons isn't there anymore. As the electrons move in one direction and leave behind holes, it will appear as though the holes flow in the opposite direction. This hole flow is conventional current.
Hole Flow

This is probably the worst legacy issue I hate about electronics, luckily it doesn't matter most of the time until you get into semiconductor physics.

Yes, thanks for the post and links. That has really cleared up my understanding. I'm happy with the idea of positive charge going one way and electrons the other.

electric noob, you have the totally wrong idea of how electron flow occurs at all. It takes minutes, hours, months, even years for a single electron to actually move from one end of a circuit to the other in a metal, and in the case of AC circuits the electrons don't actually move at all on average, what moves is the energy. Far too often people think of electronics as water flowing from one point to another, which it absolutely is not. It's energy (like a wave in water) traveling from one point to another, with electronics electrons are the media, what is being 'transferred' is energy.

Read this page
SCIENCE HOBBYIST: how transistor works, an alternate viewpoint
It's a lot to take in but explains it all.

Good post post and link. This has cleared my mind of haze. Nice article, that guy thinks the way I do and he made everything very clear. Thanks

It also was important (and still may be for the few people that still use them) in understanding the operation of a vacuum tube. Electrons boil off the hot cathode, fly through the tube vacuum, and are collected by the positive polarity plate. It doesn't make much physical sense if you try to talk about positive charges leaving the plate and going to the cathode.

This is one area that has caused me a lot of confusion because in the guitar amp world vacuum tubes are the every day norm and preference.

 

[MrAl]

Hi again,


A hole by my definition is, "The orderly absence of media and its interpretation",
however the existance (or lack of existance) of holes (as in holes in the ground)
has been the subject of debate for ages.
Semiconductor holes are almost the same if you view the electron as
a physical object, but if you view the electron as a charge then the
hole takes on a new meaning because it has a positive charge. This
positive charge is again due to the absence of media (the media being
the electrons) but there is also a charge associated with it so it takes
on a new meaning in itself.

Some examples are in the following diagram.
Fig 1 shows what looks like no holes, while Fig 2 shows what looks like
a single hole. What is this round object if there are no holes?
In language we are able to create nouns for many things that dont
really exist physically.
Fig 3 shows that we can even have holes of different shapes.
Fig 4 can be described as having no holes at all (no orderly absence)
unless we look closer and then we might say that it has lots of tiny
holes, while Fig 5 can be said to have either one hole or lots of tiny
holes and one big hole.

For more thoughts on the concept of holes take a look here:
Holes (Stanford Encyclopedia of Philosophy)

Here is the diagram: