Wikipedia talk:WikiProject Electronics/Archive 1

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Archive This is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page.

Contents

Diagrams & drawing packages

I think any diagram is preferable to no diagram. To this extent, I think the package chosen should be one that is easiest to use as long as the o/p is reasonable and the program is free to use. THis will encourage people to draw a diag, when otherwise they would not bother. The examples of all output shown on project page all look perfectly OK to me.--Light current 16:59, 22 September 2005 (UTC)

if you think there is any programme at the moment it is worth to suggest, just do it in the main page signing your words. The main page is still a draft, so you can do it. Then, we'll discuss about it. I would suggest Xcircuit, it's the one I prefered, but it has the problems I underlined in the main page. If you want to get a good output, wasting A LOT of time to get it, then your choise is inkscape...
when we'll be more people, I'll write to some developers asking for working for us. Now we are not a powerful voice: we are just three! - Alessio Damato 13:31, 23 September 2005 (UTC)
Well, with Inkscape, you can create the components first, and then reuse them later, so it's not "A LOT" more time, just "a lot" more time.  :-) — Omegatron 16:11, 29 September 2005 (UTC)
How about Wikisophia? See for example [[1]]. --HappyCamper 00:26, 17 October 2005 (UTC)

Connection dots on schematics

I think its essential to use conn dots on schematics. THose without them are so hard to understand, trying to find out if a wire is just crossing or is actually connected to another wire. So the package must support conn dots--88.109.39.70 17:06, 22 September 2005 (UTC)

Yes, definitely. But then we get into style specifications, which can make the images more consistent. European rectangle resistors vs american squigglies, arrow sources vs two circles, etc. But is it a good use of time? — Omegatron 18:17, 22 September 2005 (UTC)
Probably not worth the effort to impose this sort of uniformity. *But* if there is an international standard out there which states a preference of one over the other, I'd go for that. Sort of like the IUPAC suggesting the following spelling for aluminium. I think what is more important that we aim for clarity in any schematics that we draw. --HappyCamper 00:28, 17 October 2005 (UTC)

Symbols

When drawing resistors on paper I use the squigglies as I find it easier than drawing a rectangle. When using a CAD package I obviously use their symbols. I personally slightly prefer the squigglies but thats only because I was brought up using them. I think most packages now use rectangles for resistors and, to be honest, it does look less fussy. But I dont really mind. Current sources are usually shown as two interlinked circles with an arrow at the side denoting polarity. Voltage sorces are denoted as a single circle with an arrow at the side denoting polarity.(sharp end is positive). But diamonds are OK, its just I think circles are more standard.--Light current 23:06, 22 September 2005 (UTC)

Well, diamonds are controlled sources, which are different. I'm talking about the difference between european and american symbols:

— Omegatron 14:05, 23 September 2005 (UTC)

But when I originally mentioned it I said it was likely a waste of time. So let's drop it. We can talk about more important things. — Omegatron 14:06, 23 September 2005 (UTC)

I dont like the German ones!! Lets stick with the US ones (maybe apart from resistors)--Light current 14:15, 23 September 2005 (UTC)


I would like to revisit the topic of resistor symbols. I believe that the squiggly shape versions (as opposed the the boxes) are more intuitive and more in keeping with the ones we use for inductors. A mere box can represent anything unless you include a reference or value beside it.

Also, I'd like to suggest that we try to simplify our schematics by avoiding unnecessary power or ground connection rails, pin numbers, and adhere to a general left-to-right signal flow where possible. --Hooperbloob 04:39, 10 October 2005 (UTC)

There are instructive reasons why boxes are used in certain contexts - after all, a schematic is only an approximation to the behaviour of a circuit - the intention of a schematic is to provide a trained person to gather all the relevant information quickly, whether by noticing particular components in the circuit, quickly calculating voltages, etc ... I personally like the squigglies rather than the boxes (because they take up less room in an image). Ditto for your suggestion. --HappyCamper 00:31, 17 October 2005 (UTC)

Title

WikiProject Electronics or WikiProject Electricity?

Basically, how broad do we want it? — Omegatron 06:04, 23 September 2005 (UTC)

I think electronics will be quite broad enough!!--Light current 12:56, 23 September 2005 (UTC)
Just been rethinking! One possibility is to call it WikiProject Electronics/Electrical engineering if people want to include the heavy current/ high voltage stuff.--Light current 01:19, 25 September 2005 (UTC)

I don't think we need to worry about that for now. Remember one of the major criticisms of such a project was that we would spend all our time on bureaucracy and none on editing electronics content.  :-) — Omegatron 01:37, 25 September 2005 (UTC)

I know! but I have a lot of time!(as it says on my Talk page) ;-) Anyway if any electrical engineers suggest it in the future we can consider it--Light current 01:44, 25 September 2005 (UTC)
I think we should stick with "Electronics" at the moment. It's a comfortable level of abstraction we are working at, and it would probably warrent another WikiProject if other fields are included. That is to say, I think more than 75% of this project is focused on circuit level implementations and their idiosyncracies. --HappyCamper 00:34, 17 October 2005 (UTC)

Scope

Added a proposed statement of scope of project--Light current 14:14, 23 September 2005 (UTC)

I think we can include telecomms biomedical electrical now as we have more members.--Light current 07:49, 9 October 2005 (UTC)

Template titles

Could we please change the template names so they start with 'electron' rather than 'electro'. The existing template may imply electr-omagnets, or electro-mechanaical, electro-chemical things etc. Electron is pretty obvoius to anyone.--Light current 15:25, 23 September 2005 (UTC)

ok, good suggestion: I'll move them soon. I used "Electro" because there was an existing stub with that, but your idea is better. - Alessio Damato 16:27, 25 September 2005 (UTC)

Gaussian Filters

I have the original paper on 'Gaussian magnitude filters' by Milton Dishal and so I would be prepared to contribute a para or 2 on these filters if no one else wants to! Please let me know if you wish me to start on it.--Light current 21:07, 24 September 2005 (UTC)

why not :-) do it and good luck (and remember to add the right template to the talk pages of what you write) - Alessio Damato 16:27, 25 September 2005 (UTC)

I want to get 'O's OK on this as I think he may have wanted to do this one himself! --Light current 16:59, 25 September 2005 (UTC)

hehe. just do it. i don't own the article anymore than you do. besides, the reason i listed it was because it was on my personal to do list for a very long time and was never going to happen. — Omegatron 03:07, 26 September 2005 (UTC)
Could you give the full citation of this paper so I can obtain a copy of it? Maybe we can collaborate on this one (provided that Real Life gives me a chance to donate more time for this). Nevertheless, quite interesting... --HappyCamper 00:36, 17 October 2005 (UTC)

M. Dishal, 'Gaussian Response Filter Design', Elec. Commun., vol36, pp 3-26, 1959.--Light current 00:43, 17 October 2005 (UTC)

Xcircuit

In name of the wikiproject, I sent a private email to the only developer of xcircuit. He has been very nice: he replied to me very quickly and answered all my questions. We are still discussing about e few points, I´ll write what I learnt from the discussion in the xcircuit section of the project. I hope you don´t mind I remove the other two short comments, since the things I know replied to our doubts. I will keep you updated when I get more news. Alessio Damato 21:02, 26 September 2005 (UTC)

Electrostatics?

What is charge decay? Is it something to do with capacitors?--Light current 01:02, 27 September 2005 (UTC)

What is charge decay? Seriously, what are referring to when you say charge decay? Are you referring to electric charge? Electric charge appears to be an absolutely conserved quantity (in fact, it is the absolute conservation of electric charge that implies the existence of a gauge field to enforce local charge conservation). Can you be more specific? Alfred Centauri 02:52, 29 September 2005 (UTC)
I said on the to do list that we should create an article on charge decay. See the two linked articles. It's just the processes by which a charged conductor "leaks" charge into the environment and becomes neutral, from what I understand. — Omegatron 16:21, 29 September 2005 (UTC)
This charge decay thing might be related to the MOS Capacitors in ICs which need to be refreshed continueously. --Davy Jones 06:32, 9 October 2005 (UTC)

Have a look at the links on this subject (charge decay) on the project page!--Light current 07:27, 9 October 2005 (UTC)

Maybe this should be in an article an electrostatics if there is one. If not we create one!--Light current 00:09, 30 September 2005 (UTC)

If I missed off the links when reformatting, apologies--Light current 16:43, 29 September 2005 (UTC)

Now I understand. From what I've read at the links on charge decay, I submit that this subject is better suited for the physics project than the electronics project so I agree with LC on this one. Alfred Centauri 00:24, 30 September 2005 (UTC)

Sorry Ive just claimed Electrostatics as one of ours!!!--Light current 00:44, 30 September 2005 (UTC)

Power factor correction

I think Power factor correction could be touched up. I'm not sure if this is better under electricity or electronics, it is somewhat relevant to both. Snafflekid 21:13, 5 October 2005 (UTC)

Its sort of half and half!. I think the original author was looking at if from a utilisation standpoint and not a utilites standpoint. I tried to add stuff about PFC as the power co would see it. So we could claim it as one of ours and tidy it I suppose.--Light current 21:33, 5 October 2005 (UTC)

Progress

Its very pleasing to see so much progress being made so quickly here. As the electrican once said "Many hands make light work"!--Light current 00:07, 30 September 2005 (UTC)

I´m pleased as well, but I expected it since I just wrote the basic structure and guidelines of the project, so there was (and there is still) a lot of work to do. Thanx to everybody: we are not many people (yet), but we are working very good together :-) Alessio Damato 00:27, 30 September 2005 (UTC)

Mindstretcher article??

Hi, since I have seen that this thing of the mindstretchers was quite interesting and successful, why don´t you start a "subsection" of the project just about it?? then, all the answers we get may be moved to a proper article. A possible choice might be Wikipedia:WikiProject_Electronics/Mindstretcher or something similar. - Alessio Damato 21:43, 30 September 2005 (UTC)

Well I dont know. Its just me and Alfred having a bit of fun discussing things at the moment. Maybe when we come to some conclusions we might see what we can do with them! --Light current 21:49, 30 September 2005 (UTC)

ok it´s up to you, then you´ll take care of it (just in case). Alessio Damato 20:34, 3 October 2005 (UTC)

Yes, the arguments/discussions may have relevance to the capacitor, inductor, and transmission line pages. Or they may not! Well just have to wait and see!--Light current 23:00, 3 October 2005 (UTC)

Mindstretchers

Problems to keep you awake at night...(or send you to sleep!)

No1. Bearing in mind the pulse charged transmission line we discussed on Talk:capacitor, what is the difference between ordinary d.c and electromagnetic radiation. Is there any difference? If so what is it? (NB dc is defined here as that steady potential difference that might be observed across a charged transmission line or capacitor.) (This is NOT a trivial question). :-)--Light current 23:01, 26 September 2005 (UTC)

No2. When is a physiscal inductor not an inductor? (ie what does it really behave like at high frequencies?).(Q. Difficult)

No3a What is an electron made of? (Quite fiendishly difficult)

No3b What happens when an electron gets 'excited'. Does it have anything to do with photons?

No4 Just what is a photon exactly? (not too difficult)

N06 What is the difference between a probability wave predicting the strength of a (standing wave) electric or magnetic field, and the actual magnitude of the same electric/magnetic field standing wave.? For instance, at antinodes the probability of finding some displacement is high. At the nodes, the probability of finding displacement is low.

(1) There must be some clever angle you are working here because the term 'ordinary d.c.' is ambigious while EM radiation is not. Please explain what you mean (exactly) by the term 'ordinary d.c.'.
(2) Are you referring to an ideal inductor or a physical inductor? If you mean physical, what type of physical inductor are you asking about?
(3a) According to QED, an electron is an electron. That is, it is fundamental so it cannot be described as being composed of some more fundamental entity. On the other hand, string theorists claim that the electron is actually a fundamental thing called a string vibrating in some characteristic way. Of course, the follow-up question to this is 'what is the string made of?'.
(3b) It sometimes makes a mess... An 'excited' electron is an electron that has higher energy than some minimum it may exist in. The energy of a free electron is composed of two terms - its 'rest' energy and its kinetic energy. For a non-free (interacting) electron, there is a term related to the EM potential too. The electron interacts electromagnetically via photons and weakly via W and Z bosons.
(4) According to QED, a photon is a quantum excitation of some mode of the quantized EM field. It is, therefore, a spin 1 boson. BTW, you didn't ask 'what is a virtual photon?'. Alfred Centauri 01:59, 29 September 2005 (UTC)

No5 (Optional question). What is a virtual photon? Extra (virtual) marks for explaning this concept.

No 5: Virtual Photons

What we call the electrostatic force or Coulomb force is due to charged particles exchanging virtual photons. What we call EM radiation is due to real photons. The exchange of virtual photons between charged particles is a 'private' affair between the particles. The exchanged virtual photons cannot be directly detected. Alfred Centauri 00:38, 30 September 2005 (UTC)

Sounds like a 'cop out' to me!! If they cant be detected how do we know they really exist?--Light current 01:05, 30 September 2005 (UTC)

If one calculates the magnetic moment of the electron without considering the self-interaction with virtual photons, one gets an answer that is not in agreement with experiment. Adding in the virtual photon interactions (a non-trivial calculation!) gives a theoretical answer that matches the experimental value to better than 1 part per billion: see Anomalous magnetic moment. Alfred Centauri 10:18, 30 September 2005 (UTC)

What causes the magnetic moment? If you say spin, I shall ask you exactly what spinning means!--Light current 20:52, 30 September 2005 (UTC)

"Spin" is a quantum mechanical concept used to describe an extra degree of freedom that small physical systems like particles seem to have. The mathematical formulation of it is exceptionally beautiful, and is related to generalized angular momentum and group theory. --HappyCamper 00:46, 17 October 2005 (UTC)

No 3a (whats an electron made of?)

In QED, the electron is the quanta of a spinor valued field. You are probably familiar with a vector valued field, e.g., the vector potential and a scalar field, e.g., the scalar potential. If you rotate a vector around 360 degrees, you get the same vector. However, a spinor must be rotated by 720 degrees to get the same spinor. It is sometimes said that a spinor is the 'square root' of a vector. When Dirac set about to develop a quantum wave equation compatible with special relativity, he essentially took the square root of a quantum operator. The solutions to this equation are Dirac spinors which turn out to describe a spin-1/2 particle and its anti-particle such as the electron and positron. If one includes a magnetic field in the Dirac equation, the solution includes a term that, in the non-relativistic limit, corresponds to a particle with a magnetic moment. Thus it appears that the intrinsic angular momentum and the magnetic moment 'pop out' of the relativistic wave equation naturally. If I can think of some 'deeper' explanation later, I'll let you know. Alfred Centauri 01:25, 2 October 2005 (UTC)

When you talk about the quantum wave equation, are you referring to the non relativistic Schrodinger's wave equation? I have actually heard of that, but its really about my limit on quantum mechanics without doing much more reading!. Ifd the electron has angular momentum, I can grasp that. It is ia rotating particle, yes? The sign of the angular momentum gives the spin. A spinning electric field gives rise to a magnetic field --- is that correct? Also the spinor sound like its rotating not in a plane but up a spiral somehow-- is that correct?--Light current 01:48, 2 October 2005 (UTC)

A quantum wave equation results from replacing classical variables such as momentum and energy with quantum operators. Schrodinger's wave equation comes from the Newtonian energy-momentum relation. Dirac's equation and the Klein-Gordon equation come from the relativistic energy-momentum relation. Although the electron has angular momentum, it cannot be said that the electron rotates about an axis as that is a classical concept. The 'spin' of an electron has no classical analog. For example, if you attempt to calculate the magnetic moment from the angular momentum of the electron, you get half the value predicted by the Dirac equation. Further, one can only measure the total angular momentum and one component simultaneously due to the uncertainty principle. Lastly, a spinor should not be confused with spinning. A spinor is a geometric object that is defined by how its components transform under a coordinate transformation. As I said earlier, a spinor changes sign under a 360 degree rotation whereas a vector does not.

I don't know if this will help or not but recall that an electron in an atom has an orbital angular momentum associated with its 'orbit' around the nucleus of the atom. The problem is, the electron doesn't orbit the nucleus like the classical orbit of a planet around a star. The wave function of the electron in an atom is a spherical standing wave unlike a free electron where the wave function is a traveling wave. Take a look at the 'Picture of hydrogen orbitals' in the Hydrogen atom. These don't look like a classical particle revolving around a point of attraction yet there is an angular momentum associated with each orbital. Alfred Centauri 03:24, 2 October 2005 (UTC)

Ah Alfred, you have said something I like and pretend to understand. I quote you:
The wave function of the electron in an atom is a spherical standing wave unlike a free electron where the wave function is a traveling wave. This is the thrust of my current thinking on the nature of electrons and lines up with my previous sugesstions and I can accept this statement without trouble. This is similar to Dr. Don Eiglers (IBM research) ideas. --Light current 03:36, 2 October 2005 (UTC)

You do understand that the standing and traveling waves I refer to are related to probability density, right? I'm afraid I don't understand how that description lines up with the idea that electrons are made of EM waves. Alfred Centauri 13:27, 2 October 2005 (UTC)

Yes, but if you have an actual standing wave pattern, then the probability density is obviously of the same shape is it not? ie the wave function describes an actual standing wave as Don Eigler says.--Light current 09:33, 3 October 2005 (UTC)

The wave function is a complex valued function that represents the so-called probability amplitude. To get the probability density, one must take the product of the wave function with its complex conjugate. That is, the probability density function is the magnitude squared of the wave function. I don't know if this answers your question or not because I not quite sure what your question was! Alfred Centauri 17:54, 4 October 2005 (UTC)

Have you ever wondered why spin is only +1/2 or -1/2 for fermions regardless of the mass or angular momentum of the particle. Does this tell you anything?--Light current 23:03, 3 October 2005 (UTC)

That's not true, LC. The intrinsic angular momentum of a particle and the spin of a particle are one and the same. BTW, there is another, even more interesting (to me, at least), aspect of spin. Recall that the EM field is a vector field. A vector rotated is unchanged when rotated through 360 degrees. The photon, the quantum of the EM field is a spin 1 particle. A vector is a rank 1 tensor. In general relativity, the gravitiational field equations involve rank 2 tensors. A rank 2 tensor rotates twice as fast as a vector under a coordinate rotation. That is, a rank 2 tensor is unchanged by a rotation through 180 degrees. The graviton, the hypothetical quantum of the quantized gravitational field is thus a spin 2 particle. The Higgs boson is called a scalar particle for the reason that it has spin 0. That is, the Higgs field is a scalar field. Alfred Centauri 17:50, 4 October 2005 (UTC)

The point I'm making is that all these spin numbers are nice and simple arent they? (Like 0,+/- 1/2, 1,2 etc). Don't you find that strange when we have such a range of particles with different masses?--Light current 23:41, 4 October 2005 (UTC)

Update: Here's a link you might find interesting. But beware: this is crank material! [2]. Alfred Centauri 15:10, 2 October 2005 (UTC)

  • Milo Wolff is a crank? Really, I didn't know that was a common opinion of him. I know some of his ideas aren't expressed in any other material I've read. His concept of spherical rotation of space is intriguing to me. Snafflekid 18:28, 4 October 2005 (UTC)
Snafflekid, I think AC has a rather conservative view regarding new theories that try to explain things without recourse to exceedingly complex math. He routinely labels these new theorists as cranks. But, as we all know, some (not all) of yesterdays cranks have become some of today's great and revered scientists whose theories have been proved correct (eg Uncle Albert - curved space -- you must be mad!). --Light current 00:22, 5 October 2005 (UTC)
Why do you say its crank material? Is that because a) you disagree with it, or b) you dont understand it or c) you have no respect for the person who wrote it? Can you demolish his arguments with known facts?--Light current 09:28, 3 October 2005 (UTC)

Answer: d) because it was written by a person displaying crank symptoms such as this little tidbit from Milo:

"First, I would like to say that learning and advancing the Wave Structure of Matter is a once-in-a-life-time opportunity. This is because WSM is the first true knowledge of the basic behavior of nature that created the Universe, galaxies, Suns, planets, and we humans on Planet Earth. WSM is indeed the 'Theory of Everything' if you like.
The opportunities offered to those curious persons who cannot wait for someone else, are many and varied. What do you want? Power? success in science? Money $$$$? or Fame?"

Just $19.95 in 3 easy payments! Alfred Centauri 18:40, 4 October 2005 (UTC)

Alfred, in my opinion, some of the material seems to echo what you say about standing/traveling probability waves. Or am I misinterpreting you? If electrons are, as you say standing probabiity waves, to what does the probability refer. Is it the probabiliy of finding charge, EM energy or just something?

Then, either I wasn't clear or you simply misunderstood me. QM and QED do not attempt to answer the question "what is an electron?" and I certainly didn't say that an electron is a standing probability wave. In QM, the possible states of a particle are completely determined by the wave function. When you solve for the wave function of an electron, you are solving for the possible states of the electron. Think of it this way, if you solve for the motion of a classical particle in a force field, you end up with function of time that gives the position of the particle. You would never think of claiming that the particle IS the position function, would you? Alfred Centauri 18:16, 4 October 2005 (UTC)

Well its obvious I'm going to need to get books on QED/QM to be able to understand/discuss fully your arguments. However, I think this would be taking a detour. I was expecting a simple discussion of ideas of reality: not one involving the obfuscation of higher mathematics. All I asked was 'what is an electron made of?'. No one has, as yet, come up with a sensible answer that does not involve sophistry! If QED/QM etc can't answer the fundamental questions, what the hell use is it? We might as well be discussing the meaning of life the universe, and everything. ( Oh , sorry --- we are!!)--Light current 22:59, 4 October 2005 (UTC)

While I sympathize with your quest for the answer to your question, please consider this: if the electron is not fundamental - if the electron is made of something else - doesn't this lead to the question of 'what is that something else made of?". QED/QM are mathematical models (Interpretation of quantum mechanics) for how things work at the subatomic and atomic level. A good mathematical model is immensely useful and I can't believe that you, as an engineer, don't understand this so I'll attribute your statements above to frustration. It could be that your question is ultimately unaswerable. It may be that what is fundamental in this universe - the stuff from which everything else follows - may be nothing. After all, 0 = 1 - 1. Alfred Centauri 01:43, 5 October 2005 (UTC)

Of course I agree that a good model is invaluable in trying to solve problems, predict system responses etc, but as an engineer, usually you know what it is that you are trying to model. In the case of the electron and other elementary particles, the physicists seem to have no idea what they are trying to model. All they can come up with is a mathematical description (based purely on mathematics) that explains some of the interactions that they observe.
The scientific method is (unless I have been misinformed)
1.propose a theory (possibly based on some discoveries),
2 predict consequences of the theory and
3 test your theory for those consequences by experiment
Predicting the perfect cohesion of mathematical ideas is not science and is a disservice to science. But there again , I'm not a scientist, just a humble engineer looking for simple answers (I still believe there are simple answers. Its just that we aint found 'em yet!). BTW I get the impression you're a physicist by training. No offence meant if you are. Someones got to do the job! Finally, if everything is made from nothing, I would be happy to accept that. Its neat!--Light current 02:10, 5 October 2005 (UTC)

Your statements above reveal to me that you have no idea how the Standard model was developed. Find yourself a copy of "The Second Creation" to get an idea of the struggle to develop this model. BTW, I'd be proud to be a physicist but I'm just a TV repairman. Alfred Centauri 20:44, 5 October 2005 (UTC)

You are quite correct about my knowledge of the standard model. Thats becuase:

A) It was discovered/developed/published after I finished my formal education

B) I did not study physics, but electronics engineering and did not keep up with physics after graduation.

C) I have forgotten most of what I did learn anyway!

BTW You are far too smart to be a TV repairman.;-)--Light current 00:15, 6 October 2005 (UTC)

Follow up: I didn't address your last question in my response above. The magnitude squared of the wave function is the position probability density function. Alfred Centauri 22:51, 4 October 2005 (UTC)

OK So we have the probability of the position of something. What is the something?--Light current 23:35, 4 October 2005 (UTC)

Well, it is actually the probability that the something (whatever that is) will be measured or detected somewhere. The funny thing about QM is that it is not at all clear that the something exists at a definite location until it is detected somewhere (Wavefunction collapse). What is that something? If I knew, I would have told you by now. Alfred Centauri 01:51, 5 October 2005 (UTC)

OK Now you are coming clean. I appreciate that. We dont know what it is we are predicting with the probability waves. However, Im sure you'll agree that it is something that is being predicted. If it were not so, there would be no point in doing it. Now, does anybody know or have an inkling as to what it is that they are predicting the probabilty of finding at a certain point in space. If I were in the field, I would be asking "What the hell is it we're seeing here: charge, amplitude of electric field, amplitude of magnetic field or something else. The prime task would be to find out what it was we were actually seeing before trying to measure its probability distribution, spin, etc etc. Can you see my viewpoint? --Light current 02:24, 5 October 2005 (UTC)

I'm sorry if I led you to believe that I know what the electron 'is' as I did not intend to, so the 'coming clean' stuff isn't really applicable. Look, I'm having trouble understanding what your issue here is. The electron, as a fundamental entity, exists. It has only a few intrinsic characteristics: mass, electric charge, flavour, spin, magnetic moment and maybe a couple of others that I can't think of at the moment. To the limits of our ability to discern, the electron is point like. By the rules of QM, we can in principle, given some initial information about an electron, determine the wave function for that electron and thereby calculate the probability of finding (detecting) that electron within some volume of space at a later time. When you ask what is it we are detecting, the answer is that 'thing' that has the mass, electric charge, flavour, spin, magnetic moment etc. that we attribute to an electron. That is how we identify an electron. We can measure these properties of a particle. If we detect something that has different values for these properties, it isn't an electron. Thus, I believe your question should not be 'what is an electron?'. Instead, I believe your questions should be 'what is electric charge? what is mass? what is spin? what is flavour?'. If you can unambiguously answer these question, then you will know 'what' an electron is. Alfred Centauri 23:47, 5 October 2005 (UTC)

Thank you. I shall carefully consider your above comments. Please wait.....--Light current 00:26, 6 October 2005 (UTC)

No 3b: Excited electrons and photons

I suggest we set aside the weak interactions for the moment. What Im interested in is how exactly electrons and photons interact. They seem to consist of essentially the same thing from what I gather (EM energy).--Light current 10:49, 29 September 2005 (UTC)

Why do you say that? The quantum of EM energy is precisely the photon whereas an electron has mass (rest energy), electric charge, and flavour. Thus, it would seem evident that an electron is more than EM energy. Alfred Centauri 16:07, 29 September 2005 (UTC)

OK but we all know that mass is only energy in another form. The origin of 'charge' is something else I would like to find out about--Light current 00:42, 30 September 2005 (UTC)

I did some research and found that an electron and a positron can annihilate each other to form not only photons, but also the 'Z-naught' or 'Z-zero' weak vector boson. This particle is similar to the photon except that, due to the Higgs mechanism, it has mass and further, it couples to non-electrically charged particles such as the neutrino. Thus there is more than than 'just' EM energy 'inside' an electron. Alfred Centauri 00:32, 30 September 2005 (UTC)

So what else is inside an electron? --Light current 00:42, 30 September 2005 (UTC)

AFAIK experimentally, the electron looks pretty much like a perfect point charge in scattering experiments: it doesn't look like there's internal structure. Note that this is different from electron-positron collisions, where particles essentially coalesce out of the energy from the collision. These particles don't come from "inside" the electron and positron.
For a theoretical understanding of photon-electron interaction, you may want to study QED. - mako 23:14, 3 October 2005 (UTC)

So is an electron pure energy?--Light current 23:31, 3 October 2005 (UTC)

Depends. Have you ever tried asking questions on the reference desk? I think you would find the answers there very interesting as well. Generally speaking, at a certain level of mathematical abstraction, there is no difference between mass and energy, although the trick is to use the right model for what you want to express... --HappyCamper 00:49, 17 October 2005 (UTC)

Can we say that electrons are material particles no matter what while photons are material particles only in motion and are hypothetical at rest? --Davy Jones 07:48, 26 October 2005 (UTC)

Well no. These questions were posed in order to stimulate discussion on various electronics/physics problems. If you look around her and esp Talk:capacitor you'll see what I mean.

Semiconductor merge

I am finding that there is enough material to warrant both semiconductor and semiconductor device pages. The semiconductor page is very well written and did not need much work. And, it may be too academic for many people who are interested in components. With enough disambiguation and cross linking, the pages are becoming complementary.

I think that the transistor page could use some pruning with stuff being moved to semiconductor device. Snafflekid 01:13, 1 October 2005 (UTC)

OK thanks for your work on semiconductor & semiconductor devices. I agree that transistor is too large and needs pruning.--Light current 01:40, 1 October 2005 (UTC)

I have released semiconductor and semiconductor device into the wild. Edit at will. I will give transistor some attention when I have time. Snafflekid 07:48, 1 October 2005 (UTC)


BJT, voltage-controlled or current-controlled

When I edited the transistor page, I changed the explanation of the BJT operation from a voltage controlled device to a current controlled device. I figured sooner or later it would be questioned, and I think I understand the confusion. In circuitry the transistor is typically "controlled" by applying a voltage to the base-emitter junction, if the base-emitter voltage is above approx. 0.7V the transistor is on. There is even an equation for collector current to base-emitter voltage, Ic=Is(exp(Vbe/Vt))

A transistor is ON at any positive bias voltage. Look at the equation for collector current--Light current 02:17, 8 October 2005 (UTC)

I agree, I was restating a commonly used concept, albeit wrong. Snafflekid 23:30, 8 October 2005 (UTC) However, the meaning I use is how the physics of the BJT work (maybe the least common way of discussing the BJT control). For an NPN, holes from the base are injected into the base-emitter depletion region, which controls electrons from the emitter getting injected into the depletion region, diffusing across the base and finally collected in the collector. In reality, the BJT is a charge controlled device, but that is confusing.

I suppose if there is a better way of getting my point across on transistor, let me know. Snafflekid 00:32, 8 October 2005 (UTC)

Please consider changing this back. We have been thro this discussion, THe BJT is voltage controlled. See Bill Beatys site: amasci.com--Light current 00:37, 8 October 2005 (UTC)

Okay, you asked for it! No mention of voltage-control or current-control, but a gobsmack pile of information. BTW I read the site and I've some comments about Mr. Beatys views...after I've enjoyed my wine. Snafflekid 03:57, 8 October 2005 (UTC)

I suppose I understand the spirit of his complaint, but really I don't see why he thinks every professor and text book doesn't know how a BJT works. (I think he did not do so well in his semiconductor physics course). If his explanation helps someone understand the BJT enough to be useful, well, great. But I don't agree with a lot of it.

"By applying a small voltage between Base and Emitter, we can make the thin layer of insulator become even thinner. If it's thin enough it stops insulating and charges flow across it. (Imagine bringing two wires closer and closer until the electrons start jumping across the microscopic gap.)"

First off, depletion regions are not insulators, at least not in any true sense of the word. Charges can flow through a depletion region, they cannot do that in an insulator. Also, electrons are not jumping across this thin gap. Free electrons in the N are created at room temperature, and they are always flowing randomly around, including into the abuting P where they happen to combine with the acceptor atoms and form fixed negative charges, when enough electrons have flowed into the P, the region develops enough negative charge to repel any more electrons which happen to randomly move towards it and we reach equilibrium.
Very often (very very often) forward voltage is applied to the base-emitter junction, which "lowers the barrier" allowing less energetic electrons (and holes) to move through the depletion region and enter the neutral region of the base (or emitter), where they form the current. So, it would be technically valid to call the BJT a voltage controlled device under these circumstances, but this is not the end of the story. The reason current flows across the junctions is because something upsets the balance of diffusion and the repelling electric charge in the depletion region. I explained how voltage can do it. But voltage is not the only thing that can control the bipolar transistor. Photons striking the base-emitter junction generate electron-hole pairs, carriers which increase the number of carriers on a side of the junction, changing the diffusion constant and causing transistor action. Also, radiation particles can travel through the junction or nearby and create lots of electron-hole pairs, which can cause the B-E junction to conduct. Therefore, IMO it is the action of charge carriers moving across the B-E junction which causes current from Collector to Emitter. So, calling a BJT a voltage-controlled insulator is bunk, also IMO. A fundamental explanation of the BJT action uses charge as what controls the device. Snafflekid 23:28, 8 October 2005 (UTC)

I dont think he says actually that a BJT voltage-controlled insulator does he. He says the depletion layer in some ways acts like a voltage controlled insultor. Any way the BJT is more voltage controlled than current controlled would you not say? The question of photoelectric effects etc are neither here nor there as far as normal transistor action is involved.--Light current 00:31, 9 October 2005 (UTC)

From this link [3] it seems to me that's what Bill Beaty says. The application of voltage is one way of getting the junction to conduct, but there are other mechanisms to get carriers into the base also which turn on the transistor and have nothing to do with lowering the barrier by using voltage (completely valid and useful mechanisms). Photons and radiation, I've mentioned. Even perhaps a magnetic field using the Hall effect could inject holes into the base. A carrier imbalance somewhere in the base or emitter is going to start the bipolar transistor action. Voltage is not guaranteed to make the transistor work. For instance, voltage could be applied to the B-E junction but if carriers are being robbed by some nearby process (highly contrived situation I know) then the transistor would not turn on. Maybe this discussion seems like splitting hairs, and probably is for a vast majority, but I just wanted to be clear why I think the carriers are the fundamental controller of the transistor. However, I doubt that declaring in the article the BJT as a carrier-controlled device is helpful. So I changed the article to what happens in the BJT and let people draw their own conclusion. Snafflekid 01:37, 9 October 2005 (UTC)

Ah yes that's his short version. The long version is better. We all? know how to turn on a transistor and we dont use a battery across the BE. But sometimes we do use the voltage drop across a diode as per current mirror don't we?. If you maintained the BE voltage at say 0.65 V are you saying that there is a condition where it would not have any collector current flowing?. I've not heard of this one. Do you have any details?--Light current 03:02, 9 October 2005 (UTC)

Do all accelerating charges radiate?

Have either of you 2 seen this [4] It does seem to cast some doubt on whether accelerating charges do in fact radiate!--Light current 01:02, 6 October 2005 (UTC)--Light current 01:16, 6 October 2005 (UTC)

I have no idea what that guy is talking about. Read any textbook. They all say that accelerated charges radiate. Pfalstad 02:13, 6 October 2005 (UTC)

It seems fairly clear to me. Have you read thro' it? The textbooks truncate the proper equation and therefore give the wrong answer. The correct answer is that the acceleration has to be cyclic (oscillation like SHM) for radiation to occur. Uniform acceleration does not produce radiation. If it did, then every piece of charged wire in the earths gravitational field would be radiating due to the accelerating charges!.--Light current 03:22, 6 October 2005 (UTC)

Weird. I didn't read it because I figured it was some crank. (Which it still might be.) But this is a real problem introduced by general relativity. [5] This has nothing to do with classical electrodynamics, though, where accelerating charges radiate, period. Please don't confuse the kids by talking about general relativity in an article about capacitors.  :) Pfalstad 03:50, 6 October 2005 (UTC)

No its not my intention to try to confuse anyone and I certainly dont want to mention GR in the article. Can AC use classical dynamics to solve his problem though - or must he use QED? He has not indicated his line of investigation to us as yet. However, this is really a side issue AFAIC. My main hobby horse at the moment is the importance of EM radiation inside charging and charged capacitors and TLs and whether this tells us anything about the nature of EM radiation, its generation and how EM rad relates (if it does at all) to steady (dc) voltage. The earlier posts on this page will give you a flavour of what AC and I have been discussing at length. When you say accelerating chages radiate, do you still maintain that they do under uniform (constant) acceleration?--Light current 05:10, 6 October 2005 (UTC)

Yes I do, but how does uniform acceleration have anything to do with this topic? Pfalstad 06:34, 6 October 2005 (UTC)

Probably doesnt have much to do with it at the moment. But how do you explain charged objects in the earths gravitational field. Do they radiate?--Light current 04:33, 8 October 2005 (UTC)

That's actually an excellent question. I don't know enough about general relativity to answer. My impression is that a lot of physics bigwigs would have trouble answering too. From a classical or special relativistic perspective, the charges aren't moving or accelerating, of course they don't radiate. The charges in capacitors are not uniformly accelerating so this doesn't matter anyway. Pfalstad 05:47, 8 October 2005 (UTC)

Charges do not accelerate uniformly in a capacitor, you say? You may be correct. But what happens when the charges reach the edges of the plates? THey should then be accelerated non uniformly and radiate. Yes? :-)--Light current 17:41, 8 October 2005 (UTC)

yes... also I thought about this and talked to someone who did PhD work in GR. He pointed out that the amount of radiation from gravity is very very small. For one thing, only free charges radiate. Electrons bound in atoms do not radiate, because the + and - charges are close together so that radiation, if any, is of opposite phase and cancels out. But take 1 coulomb of free charge. This is a huge amount; a 10 cm sphere charged with 1 coulomb has a potential of 90 billion volts. But the amount of radiation from such a mass of charge due to gravitational acceleration is 2x10^-14 watts, according to Larmor's formula.
also, the charges in our world are involved in much more substantial electromagentic interactions which produce much higher acclerations than g, swamping the effect of g. (vibrations, heat, etc.) and most importantly, at the level of quantum models, the whole thing is suppressed by quantization effects which produce gaps between allowed energy levels for the bound charges. so the electrons don't normally radiate because there are no energy levels for them to jump down to. But if the acceleration were large enough they would, even if uniform. Larmor's formula is a nonrelativistic, nonquantum formula. So we're both wrong, or right. You can ignore small accelerations and focus on the large ones, even if "uniform", whatever that means (constant throughout all time?). Pfalstad 20:19, 8 October 2005 (UTC)

OK.Pfalstad. As I said this is not my main hobby horse and I think its a very difficult and controversial question that I'm not realy qualified to answer. So I think I'll leave it there. THanks for the discussion. I have just put the extract below if any other interested parties want to stretch their minds! But I dont think I'll be continuing this one.--Light current 21:21, 8 October 2005 (UTC)

Heres an extract from mathpages [6] on the subject of radiation from accelerating charges. does it pose a paradox and call into question Larmour's formula?

Does A Uniformly Accelerating Charge Radiate?

One of the most familiar propositions of elementary classical electrodynamics is that "an accelerating charge radiates". In fact, the power (energy per time) of electromagnetic radiation emitted by a charged particle is often said to be strictly a function of the acceleration of that particle. However, if we accept the strong Equivalence Principle (i.e., the equivalence between gravity and acceleration), the simple idea that radiation is a function of acceleration becomes problematic, because in this context an object can be both stationary and accelerating. For example, a charged object at rest on the Earth's surface is stationary, and yet it's also subject to a (gravitational) acceleration of about 9.8 m/sec2. It seems safe to say (and it is evidently a matter of fact) that such an object does not radiate electromagnetic energy, at least from the point of view of co-stationary observers. If it did, we would have a perpetual source of free energy. Since the upward force holding the object in place at the Earth's surface does not act through any distance, the work done by this force is zero. Therefore, no energy is being put into the object, so if the object is radiating electromagnetic energy (and assuming the internal energy of the object remains constant) we have a violation of energy conservation.

--Light current 17:21, 8 October 2005 (UTC)

Inside a capacitor or electronic device, electrons move within a crystal structure. Think valence bands, etc. - mako 19:07, 8 October 2005 (UTC)

Does a capacitor have a crystal structure? I've not heard of this one!--Light current 03:17, 9 October 2005 (UTC)

I think all conductors (metals, semiconductors, superconductors, etc.) have a crystal structure. Not sure how this relates to the accelerating charge topic though. Pfalstad 04:34, 9 October 2005 (UTC)

No neither am I! A capacitor has not been redefined as a semiconductor has it? ;-)--Light current 04:39, 9 October 2005 (UTC)

Pfalstad mentioned it above: electrons in bound states don't radiate. Therefore the accelerating charge topic doesn't exactly relate to the electronics at hand. It's an interesting problem, but be wary of mixing relativistic and classical concepts. - mako 07:52, 9 October 2005 (UTC)

Hoe do LEDs work then? ;-)--Light current 14:24, 9 October 2005 (UTC)

electrons transitioning from one bound state to another do radiate. Calling it "acceleration" is kind of a misnomer here. It's a quantum effect. Larmor's formula probably doesn't apply. Pfalstad 18:23, 9 October 2005 (UTC)

OK Case closed then (for now)!--Light current 22:56, 9 October 2005 (UTC)

I dont want to break ur heart, but hasn't that got to do with the transition of outermost electron from higher orbital to lower? --Davy Jones 08:02, 26 October 2005 (UTC)