This electons flowing rubbish - Page 1
Forum section: electronics / general

author: Terry Bites
author_rank: Super Contributor
timestamp: March 01, 2021, 02:24:14 pm
content: Why do people just keep on promoting bad science?Electrons do not flow in conductors or semiconductors or anything else when a current is flowing. Yeah Yeah drift current... diffusion current... blah.Charge is transported around the current path under the influence of the applied voltage.Let's stamp out the BS in EE!

author: TimFox
author_rank: Super Contributor
timestamp: March 01, 2021, 02:56:44 pm
content: There are exceptions to your absolute statement. For example, electrons do flow from a hot cathode to the anode under "saturated" condition (not limited by space charge), with the resulting shot noise in the current in the rest of the circuit. (Space charge modifies the equations, but the flow to the anode is still a host of electrons at a reasonable velocity.)Usually in the first chapter about "current" in an undergraduate physics textbook on electromagnetism there will be a list of examples of different physical situations where there is current flow, including the vacuum diode above.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 01, 2021, 03:27:57 pm
content: I suppose it's tricky. A hydraulic analogy is quite productive. There, too, the drift and particle velocities are widely disparate; perhaps one should be careful to emphasize the relevance of the speed of sound (mean velocity of molecules) in that case, and show the analogy with electron drift.But it's also hard to motivate that; you can't splash some water around and say that it happened at the speed of sound, no, it's much too fast to see. It's easily illustrated with resonators and frequency or step response, but those require much more knowledge (dynamics, wave mechanics) to understand. Worst of all, electron waves flow at the speed of light in the medium, not at the thermal velocity, so the analogy again breaks down, in a different way.And neither case seems to be good preparation for the student, for the truth that alternating current flows largely in the space between conductors, rather than in them (in the bulk) as such.Tim

author: IanB
author_rank: Super Contributor
timestamp: March 01, 2021, 03:40:48 pm
content: Quote from: Terry Bites on March 01, 2021, 02:24:14 pmSo I'm slightly curious. How is charge transported around the current path without mobile charge carriers?

author: TimFox
author_rank: Super Contributor
timestamp: March 01, 2021, 03:46:27 pm
content: In simplistic terms, I like to think of current flow through a normal solid conductor as a slight tendency of a zillion electrons to move to the right under the influence of the potential difference from left to right, superimposed on their random thermal motion that exists even without applied voltage.

author: bdunham7
author_rank: Super Contributor
timestamp: March 01, 2021, 04:06:43 pm
content: Quote from: Terry Bites on March 01, 2021, 02:24:14 pmNo model is perfect, but that doesn't mean we throw them out when science reveals a new refinement or wrinkle. Your assertion is along the lines of those who claim Newton waswrongbecauseF=MAis 'bad science' just because it appears to not be exactly true in some regards.For DC current, the average velocity of the electrons in a conductor would be easily calculated if you know the number of electrons moving (the current), the length of the wire and the number of the electrons in the wire. The only tricky part is that this gives you the average velocity ofallthe electrons, not just the ones that actually move. So now you have to define your terms and see if you want to just count the ones that actually move and then you have to see if you can determine that number for your material.https://en.wikipedia.org/wiki/Drude_model#Drude_response_in_real_materialsLike any model, especially those predating quantum physics and relativity, Drude has its limits. That doesn't make it 'bad science'.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: March 01, 2021, 04:22:12 pm
content: How do these work?

author: penfold
author_rank: Frequent Contributor
timestamp: March 01, 2021, 04:35:44 pm
content: Would a change in terminology make it better? We could have "a flow of current caused by a floundering of electrons"

author: JohnnyMalaria
author_rank: Super Contributor
timestamp: March 01, 2021, 06:09:59 pm
content: Quote from: Terry Bites on March 01, 2021, 02:24:14 pmIt's not bad science. It's an appropriate model to explain the observed phenomena and allow us to exploit those phenomena. Unless you taught everything from the perspective of Unified Field Theory, then it would all be bad science, too.Is teaching Newton's law of gravity bad science?

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: March 01, 2021, 06:35:24 pm
content: Oh and what are "electons"?

author: RoGeorge
author_rank: Super Contributor
timestamp: March 01, 2021, 07:06:18 pm
content: Quote from: Terry Bites on March 01, 2021, 02:24:14 pmI don't know, but that's exactly what you are doing right now. You are promoting bad science.Quote from: Terry Bites on March 01, 2021, 02:24:14 pmElectrons do flow. If you are upset for why they do not flow in a straight line, then you shouldn't. Wrong expectation. Flow is not necessarily in straight line, in fact it's almost never in a straight line.Does water flow? Water molecules also wiggle around while flowing.Does air flow? Gas molecules have an even larger Brownian motion.Looks like it's correct to say electrons flow, too, thought the most widespread expression is "a flow of electrons".Quote from: Terry Bites on March 01, 2021, 02:24:14 pmCould be like that, but not necessarily.Charges can be moved by other means than applying a voltage. For example, you can put charges on a piece of plastic then mechanically move the plastic band, and you'll have a current flow without applying any voltage.As a generic advice, when the whole world seems wrong yet you seem right, usually it means you misunderstood something, or you are missing something. Don't use emotional words like "rubbish", "blah" or "bullshit", don't be judgemental and don't act superior calling for the wrong action "let's stamp out".Better, explain what contradiction you noticed, then ask "what am I missing?"

author: Gyro
author_rank: Super Contributor
timestamp: March 01, 2021, 07:48:11 pm
content: Quote from: Alex Eisenhut on March 01, 2021, 04:22:12 pmAh, those are CathodeRays

author: Cyberdragon
author_rank: Super Contributor
timestamp: March 01, 2021, 09:00:01 pm
content: Quote from: Gyro on March 01, 2021, 07:48:11 pmYou confuse rays with beams, D! Minus! I'd give you an F, but that would mean seeing you in summer school.

author: JohnnyMalaria
author_rank: Super Contributor
timestamp: March 01, 2021, 09:14:43 pm
content: Time for an educational intervention:

author: Sal Ammoniac
author_rank: Super Contributor
timestamp: March 01, 2021, 10:57:56 pm
content: Quote from: IanB on March 01, 2021, 03:40:48 pmThe same way momentum is transported in one of these:

author: Brumby
author_rank: Unknown
timestamp: March 02, 2021, 12:11:45 am
content: Quote from: Terry Bites on March 01, 2021, 02:24:14 pmQuoteYou can leave whenever you like.

author: JohnnyMalaria
author_rank: Super Contributor
timestamp: March 02, 2021, 12:17:45 am
content: Quote from: Terry Bites on March 01, 2021, 02:24:14 pmUm, what about situations where the movement of electrons (or other charged particles) generates the voltage???

author: IanB
author_rank: Super Contributor
timestamp: March 02, 2021, 03:25:18 am
content: Quote from: Sal Ammoniac on March 01, 2021, 10:57:56 pmThat's AC, not DC. Try to make Newton's cradle work in only one direction without a net movement of the balls through space.

author: thermistor-guy
author_rank: Frequent Contributor
timestamp: March 02, 2021, 04:57:18 am
content: I guess the OP's point is that electron flow in circuits is rarely ballistic; in most cases, "electron flow" should be read as "net electron flow".Yes, ok. EEs know that.Quote from: Terry Bites on March 01, 2021, 02:24:14 pmNot always. One example: a crystal radio set. Entirely passive, no voltage is applied to the circuit, rather a travelling electromagnetic fieldAnother example: solar cell with load. No voltage is applied to the circuit, just a travelling electromagnetic field at optical frequencies.Other examples : thermocouples and thermopiles generating an electrical current due to a temperature difference.Energizing a circuit does not always mean applying a voltage to it. There are other sources of energy. EEs know that. Hobbyists know that.

author: Cyberdragon
author_rank: Super Contributor
timestamp: March 02, 2021, 06:37:06 am
content: Quote from: JohnnyMalaria on March 02, 2021, 12:17:45 amWhat about superconductors?*drops mic* *leaves*

author: jonovid
author_rank: Super Contributor
timestamp: March 02, 2021, 07:09:31 am
content: I have the faith to believe in what my eye's can not see. and the test equipment to prove it to be true.

author: Berni
author_rank: Super Contributor
timestamp: March 02, 2021, 08:13:49 am
content: So by this logic i can no longer say that "water is flowing along my pipe" because the water molecules are actually whizzing around wildly in all directions trough brownian motion but on average they end up going slightly more towards one direction, so that on average the water ends up moving forwards trough the pipe. So from now on i should say that "water is diffusing under the influence of unequal pressure caused by statistical collisions trough varying proximity trough the cavity of my pipe"It is perfectly acceptable to simplify a concept down to what matters for the use case. If you are a physicist putting together some physics experiment involving charged particles then yes you would care about it. If you are an electronics engineer designing a transistor amplifier circuit you just don't give a toss about the fine details of what electrons are doing, all you care is the current flowing trough your components. Those currents also create magnetic fields around your circuit that can induce other currents, but you know your circuit is only working with 10KHz so you also don't give a toss about those because even tho the effect is there, it is too tiny to actually affect anything.Its not that engineers say "these weird hand wavey mumbo jumno things don't exist, we just have current flowing trough a wire" they actually say "These fine details of what happens don't really matter in my particular case since it doesn't affect the operation of my circuit, so i can safely simplify it down or ignore it without any adverse effects, great so i can just slap on ohms law and have my circuit finished by the end of the shift"

author: Terry Bites
author_rank: Super Contributor
timestamp: March 02, 2021, 01:28:58 pm
content: Thinking of the electron as a particle is another poor analogy. It's a particular disturbance in a system of fields.Is your anode getting heavier?

author: tszaboo
author_rank: Super Contributor
timestamp: March 02, 2021, 01:49:45 pm
content: It's just terminology. If everyone knows what "current" means, and its not a river, but a wire, what's the point of changing it? People dont confuse electronics calculations with hydrodynamics. Probably because hydrodynamics is more complicated.And then there are electron holes, technical current, condenser microphone ( I guess to turn steam of sound into electrons), and so on. Do you also want 14 year old students to understand quantum physics, before they draw the circuit with the battery-switch-lamp? How about explaining how this current is transformed into heat, that is then turned into light?

author: madires
author_rank: Super Contributor
timestamp: March 02, 2021, 01:53:44 pm
content: Quote from: penfold on March 01, 2021, 04:35:44 pmADHD electrons?

author: Stray Electron
author_rank: Super Contributor
timestamp: March 02, 2021, 02:12:20 pm
content: Quote from: madires on March 02, 2021, 01:53:44 pmI saw what you did there!

author: Berni
author_rank: Super Contributor
timestamp: March 02, 2021, 02:12:25 pm
content: Quote from: Terry Bites on March 02, 2021, 01:28:58 pmBut why would we talk about an disturbance in an electric field? That electric field is just a large scale manifestation of the effects caused by quantum electrodynamics.https://en.wikipedia.org/wiki/Quantum_electrodynamicsBasically you can keep digging deeper and deeper with this, so far the deepest depth for this is QED. Its the same as we thought atoms are the smallest building block. Then we figured out how to bust the atom open and find those protons and neutrons inside. Suddenly those ware the fundamental particles. But then we figured out how to punch those protons so hard that they break into even smaller more fundamental particles. But the way an atom behaves is still valid, even if we found out its actually made up from smaller particles that are made up of even smaller particles. We don't have to throw chemistry out the window because of it.

author: JohnnyMalaria
author_rank: Super Contributor
timestamp: March 02, 2021, 02:14:43 pm
content: Quote from: Berni on March 02, 2021, 02:12:25 pmThe Unified Field Theory is even more fundamental.

author: penfold
author_rank: Frequent Contributor
timestamp: March 02, 2021, 04:54:14 pm
content: Quote from: Stray Electron on March 02, 2021, 02:12:20 pmSo there we go, it defines their two states of "lots of movement, very little of it in the intended direction" and "nothing but direction although sometimes in an unexpected direction" (apologies Stray Electron if it appropriates your username)

author: ledtester
author_rank: Super Contributor
timestamp: March 02, 2021, 05:43:43 pm
content: Are you concerned that it's not the same electron that skips from atom to atom?Problem solved:https://en.wikipedia.org/wiki/One-electron_universe

author: JohnnyMalaria
author_rank: Super Contributor
timestamp: March 02, 2021, 05:51:56 pm
content: Quote from: ledtester on March 02, 2021, 05:43:43 pmI remember my high school physics teacher explaining this in 1981!

author: TimFox
author_rank: Super Contributor
timestamp: March 02, 2021, 09:43:27 pm
content: Quote from: JohnnyMalaria on March 02, 2021, 12:17:45 amThe only examples I can think of where the electron current generates a voltage (as opposed to being the result of an applied voltage) are:1. Photovoltaic cells, under illumination.2. A vacuum diode (or other tube) with a hot cathode and a resistor from the anode (or grid for a triode) back to the cathode, where the energetic electrons thermally emitted from the cathode induce a current in the (usually high-value) resistor. Beta emission from a radioactive source would be similar.In the case of induction from a changing magnetic field, the changing flux linking the circuit induces an EMF around the circuit, which then causes current to flow through the conductors and other elements of the closed circuit.

author: JohnnyMalaria
author_rank: Super Contributor
timestamp: March 02, 2021, 10:06:45 pm
content: Quote from: TimFox on March 02, 2021, 09:43:27 pmThe solar wind is a good example.Also streaming potential and sedimentation potential (ions rather than electronsper sebut the same idea).

author: jh15
author_rank: Frequent Contributor
timestamp: March 03, 2021, 05:20:20 am
content: Long distance runner without a jock.

author: GlennSprigg
author_rank: Super Contributor
timestamp: March 03, 2021, 01:14:27 pm
content: Quote from: Terry Bites on March 01, 2021, 02:24:14 pmI'm sorry my friend, but I can't even grasp what/(why) you are trying to say, thereI think you might beintermixing & confusingyourself with a few basic electrical facts....Firstly, ofCOURSEelectrons actually physically flow in conductors, but maybe not in the way 'you' imagine it.Let'sfirstclear up thoughts of the "Speed of Light". TheONLYthing that travels at the speed of light, isLIGHT.(And it does that at slightly varying speeds, whether through vacuum/air/diamond etc.! ). This actually hasnothingto do with the apparent 'speed' ofElectricity, which is simply the result of a 'knock-on' effect withinthe conductor. In say a 'Super-Conductor' situation, this knock-on effect is just a lotquicker!Now... My actual 'numbers' here are just to give you an idea, but even though, (talking aboutDCfirst!) whena difference of potential (voltage) is 'pushing' Electrons in one end of say a wire, and the apparent 'flow' isalmost instantaneously apparent at the other end, theElectronsthemselves did NOT actually travel that fast!Assuming that in a conductor, there is say 1-Amp flowing, then the ACTUAL physical 'Electrons' are only movingat (ABOUT!) say1-CmperSecond!! And 'moving' in this way, they most certainly are !!!However, for an AC circuit, (say 50/60 Hz), these 'same' electrons are just movingforwards&backwardsagain,in the same piece of wire! and never really getting anywhere... But 'moving' they most certainly are!

author: madires
author_rank: Super Contributor
timestamp: March 03, 2021, 02:12:07 pm
content: And don't forget the Fermi energy! That way it's easy to tell conductor, semiconductor and insulator apart.

author: vad
author_rank: Frequent Contributor
timestamp: March 03, 2021, 03:20:04 pm
content: Quote from: Terry Bites on March 01, 2021, 02:24:14 pmNo, no, no. That’s also wrong.I would say: charged particles (such as electrons, ions) and quasiparticles (such as electron holes) transported by electromagnetic field.PS. Should we also declare air flow a BS?

author: AntiProtonBoy
author_rank: Frequent Contributor
timestamp: March 03, 2021, 04:27:24 pm
content: Quote from: ledtester on March 02, 2021, 05:43:43 pmAh but where are the positrons?

author: ejeffrey
author_rank: Super Contributor
timestamp: March 03, 2021, 09:30:42 pm
content: Quote from: GlennSprigg on March 03, 2021, 01:14:27 pmThis is also wrong. Speed of light has *everything* to do with the speed of "electricity" (i.e., the speed signal propagation within a circuit). Specifically it is the speed if light in the dielectric surrounding the metal. In normal situations it doesn't depend on the metal properties at all. It's the same in superconductors. This is roughly because it is light: circuit behavior is governed by electric and magnetic fields which propagate at the speed of light. The reason it depends on the speed of light specifically in the dielectric surrounding the conductors is because electric fields and high frequency magnetic fields are nearly zero inside the conductor.

author: MIS42N
author_rank: Frequent Contributor
timestamp: March 03, 2021, 09:55:01 pm
content: Quote from: Terry Bites on March 01, 2021, 02:24:14 pmOf course the OP is right. No 'electons' involved. But ... assuming we are talking of electrons ...Let's turn the question around - when does an (electrical) current flow without the movement of electrons? Anybody? nobody with their hand in the air?QED - reductio ad impossibile

author: TimFox
author_rank: Super Contributor
timestamp: March 03, 2021, 10:13:23 pm
content: A beam of positive ions (e.g. protons or ionized heavier atoms such as alpha particles) through an electrostatic field from source to target. Traditionally called “canal rays” (q.v.).

author: MIS42N
author_rank: Frequent Contributor
timestamp: March 03, 2021, 10:46:58 pm
content: Quote from: TimFox on March 03, 2021, 10:13:23 pmTo create positive ions, have to move electrons as well. They will migrate through the environment to recombine with the ions at the destination. Similar to P doped semiconductor. To create an electrostatic field strip or add charge carriers (electrons or +ve body - ion, proton etc). To regain status quo, move a carrier of the other potential. Somewhere in the process an electron is moved.I guess I have to revise the statement because in theory charge can be moved by positrons in an anti matter environment. Is there any negative charge carrier other than an electron in the "normal" universe?

author: Circlotron
author_rank: Super Contributor
timestamp: March 03, 2021, 10:57:12 pm
content: Quote from: Alex Eisenhut on March 01, 2021, 06:35:24 pmThe force that moves politicians along a path one by one through a seat of power, then down the line to obscurity.

author: TimFox
author_rank: Super Contributor
timestamp: March 03, 2021, 11:03:13 pm
content: Quote from: MIS42N link=topic=272082.msg3493046#[supThere are muons (another negatively charged lepton). In everyday life, there are Cl-ions in saline solutions which migrate in the opposite direction from the Na+ions during ionic conduction. You can have a current around a rotating disc if you have positive or negative electrostatic charges on the rim. Please refer to undergraduate textbooks.

author: MIS42N
author_rank: Frequent Contributor
timestamp: March 04, 2021, 12:13:02 am
content: Quote from: TimFox on March 03, 2021, 11:03:13 pmThe charge carrier in a Cl-ion is an electron. It's piggybacking on a Chlorine atom that's moving. Put an electrostatic charge on a disk and rotate it. Rotation is a movement. Ignoring exotic particles, electrons have to be moved at some time for a current to flow. The electron might not be the focus of attention (such as when a stream of protons is created) but it's moving in the background. Conservation of charge says it has to. Is there something in an undergraduate textbook that contradicts this? This is getting ridiculous. I think the OP put the proposition mischievously.

author: bdunham7
author_rank: Super Contributor
timestamp: March 04, 2021, 12:49:01 am
content: Quote from: MIS42N on March 04, 2021, 12:13:02 amBy that logic and by invoking 'conservation of charge', surely the inverse must also be true? So if there is current in a wire, explain where the proton (or positive charge carrier of your choice) motion is?

author: Stray Electron
author_rank: Super Contributor
timestamp: March 04, 2021, 01:12:34 am
content: Quote from: AntiProtonBoy on March 03, 2021, 04:27:24 pmHiding out in their non-gender-specific rest rooms?

author: JohnnyMalaria
author_rank: Super Contributor
timestamp: March 04, 2021, 01:15:45 am
content: Quote from: AntiProtonBoy on March 03, 2021, 04:27:24 pmCharged with indecent exposure.

author: Stray Electron
author_rank: Super Contributor
timestamp: March 04, 2021, 01:50:04 am
content: Quote from: JohnnyMalaria on March 04, 2021, 01:15:45 amCirculating in public?

author: penfold
author_rank: Frequent Contributor
timestamp: March 04, 2021, 02:10:20 am
content: Quote from: Stray Electron on March 04, 2021, 01:50:04 amI don't think anybody's objected to *circulating*, just as long as they're not *flowing* in places they're not meant to

author: AntiProtonBoy
author_rank: Frequent Contributor
timestamp: March 04, 2021, 02:47:22 am
content: Quote from: GlennSprigg on March 03, 2021, 01:14:27 pm*Puts on The Hat of Pedantry...* That's not quite true either.The speed of light happens to be an emerging property from thespeed of causalityin space-time. In other words, there is a constraint on the causal connections that matter and energy experience with everything else around it. For example, if a charged particle is neutralised somehow, its field caused by the charge will collapse at the speed of light, and all other particles nearby will remain unaffected until some time later. Another example, the gravitational effects from merging black holes propagate at the speed of light via gravitational waves, and nearby stellar objects will not observe the oscillating gravitational pull until some time later. Yet another example, an excited electron returns to its ground state in its orbital around an atom, releasing a propagating electromagnetic field, which takes time before it interacts with other matter nearby. These are all examples of causal connections exerted by one object to another, with an upper limit on how quickly such connections are mediated across space and time.

author: MIS42N
author_rank: Frequent Contributor
timestamp: March 04, 2021, 03:41:46 am
content: Quote from: bdunham7 on March 04, 2021, 12:49:01 amNo. Normally net current is zero. Electrons in a wire are balanced by electrons moving in the opposite direction (in another wire, in earth return, etc).

author: thermistor-guy
author_rank: Frequent Contributor
timestamp: March 04, 2021, 09:13:30 pm
content: Quote from: Terry Bites on March 02, 2021, 01:28:58 pmElectron as a charged particle is a great model, in many circumstances.There are useful extensions of it, such as small polaron hopping conduction in thermistors, which physicists often use.But now I know you're trolling. Thanks for the laugh.

author: GlennSprigg
author_rank: Super Contributor
timestamp: March 05, 2021, 01:21:32 pm
content: Quote from: AntiProtonBoy on March 04, 2021, 02:47:22 amAnd previously 'ejefrey' had said...Quote from: ejeffrey on March 03, 2021, 09:30:42 pmFirstly, I am aware I over simplified my statement that the 'only thing at the speed of light, is light'.However, Iwas notbranching into the likes of 'Radio-Waves', or 'Magnetic Pulses' etc etc. but was talking about thereal physical flow of actual Electrons, within say a conducting piece of Wire. Now can that be a complex scenario??YES!For example, it has been proven/demonstrated/shown & allowed for, that at much higher frequencies, MOST of the said'current' can be within the 'outer shell' of a so-called solid 'conductor'. And as such, 'Tubes' can be as effective in manycircumstances!! However, that involves actual 'Physics' that is beyond this topic of this discussion!Please donottalk about apparent 'charges', or Photons/Positrons etc, and especiallyNOTabout 'Positive-Holes' etc whichhas never had any constructive 'reasoning', except to try/(fail!) to simply accept that it is ELECTRONS that move...Actual Electrons MOVE along a physical conductor, and in a way like I described, whether people like/understand it or not!I fail to understand, why that simple process can not be believed/grasped/understood???