Talk:Capacitor/Archive 1

message: copied from earlier post
What about a dielectric t-line? When I say dielectric t-line, think fiber optic cable. Alfred Centauri 03:34, 14 September 2005 (UTC)
replies: text: EM radiation contains energy in the magnetic field too.  Since an inductor stores energy in a magnetic field, why not claim that a FO cable is an inductor also? Alfred Centauri 03:04, 18 September 2005 (UTC)
thread_title:  Fabry-Perot Resonator -- a capacitor for light? 

message: Im not going to go as far as saying an electron is ONLY an EM wave. As we have established earlier, it seems no one knows exactly of what an electron consists. However, certain of its attributes may be explainable in terms of EM waves.--Light current 16:53, 13 October 2005 (UTC)
replies: text: Yes, I can; it's because your model is wrong.  In a lossy TL, using this model, losses would damp out the waves you just described very quickly; but a real TL maintains its charge, once charged (except for leakage currents through the dielectric, ionized air, etc).  Also, in a lossy TL, dispersion would mess up the nice square edge of the waves, so that they wouldn't line up nicely anymore and would no longer add up to flat DC.  This shows that you cannot accurately model a charged TL as a combination of traveling waves.  Pfalstad 18:40, 12 October 2005 (UTC)
replies: text: Sorry, but that violates the very principle of superposition that you idea hinges on.  You claim that the steady state voltage on the line is the result of the superposition of traveling waves.  For consistency, you must also superpose the currents associated with the traveling waves.Even if the resultant current is zero, the power loss to the resistance in the conductors of the TL will be non-zero.  That is because power in a resistance is non-linear in the current.  I'm wrong - you must take the superposition sum before calculating power just as you stated.  Alfred Centauri 14:36, 13 October 2005 (UTC)

text: I think I would have asked the same questions, especially, "what's the point?"  Pfalstad 18:40, 12 October 2005 (UTC)
replies: text: Don't keep us in suspense.  What are the implications?  Pfalstad 03:34, 13 October 2005 (UTC)

text: Well any source of DC has to create some small amount of radiation when starting or stopping a current.  I wouldn't consider it a source of radiation though.  The radiation is just a side effect of the changing current.  The charges in a TL need to be present and mobile.  You seem to be minimizing the role of electrons.  There are many effects such as the photoelectric effect, vacuum tube behavior, the effect of temperature on resistance, the Millikan oil drop experiment, etc. which require electrons to explain.  Whereas these counter-propagating waves you postulate don't seem to have any measureable effects at all.  Pfalstad 16:19, 16 October 2005 (UTC)

text: What are you saying about electrons then..  They exist, but don't move?  They don't move in TL's?  TL's would work even if they didn't move?  If conductors don't have mobile charge carriers, why do conductors reflect EM waves?  Dielectrics aren't really a comparison because they reflect EM waves very weakly.  Quantum mechanics can show that conductors have band structures that enables electrons to easily move.  Dielectrics don't.  Pfalstad 21:16, 16 October 2005 (UTC)

text: I vote (c), although I only consider the leading edge (the changing part) to be a wave.  Pfalstad 20:46, 16 October 2005 (UTC)

text: It sounds like you are proposing a different interpretation of the physics rather than new physics, right?  Well I suppose you're welcome to do that.  If it can't be falsified by experiments, it's just an interpretation.  I don't find it compelling personally.  But if you like it, great.  Pfalstad 20:46, 16 October 2005 (UTC)
replies: text: Someone appears to have forgotten or has chosen to ignore one crucial aspect of EM waves - the electric field associated with an EM wave in free space is non-conservative.  The steady voltage on the TL in the example above can only be created by a conservative field - a field created by the differing charge densities on the conductors of the TL.  Alfred Centauri 20:45, 12 October 2005 (UTC)
thread_title:  Chapter 4 Hand waving 

message: :LC, is this news to you?  This result is from freshman physics.  Classically, an accelerated charge creates EM radiation (no matter how small the acceleration) .  Alfred Centauri 23:08, 5 October 2005 (UTC)
replies: text: Well hell, you claim to be patiently trying to explain to me how EM really works but you don't even seem to be familiar with this basic result.  Now, I understand why I can't seem to communicate well with you.  I have been under the impression that you understood some basic concepts but that appears to have been an error on my part.  Of course, I could be wrong about this and you might just be yanking my chain.  Why don't you come clean? Alfred Centauri 01:36, 6 October 2005 (UTC)

text: If a current terminates within some volume, there must be some acceleration of charge involved and thus radiation.  Your calculation indicates that this radiation is virtually nil.  I'm attempting to make the calculation from a different angle that I happen to find interesting.  I think LC believes that I am trying to prove something about displacement current but that really isn't the case in this particular instance. Alfred Centauri 16:28, 5 October 2005 (UTC)
replies: text: It's not tricky.  The electric field builds up between the plates.  And the magnetic field builds up as the field increases.  This produces some radiation, if the current going into the capacitor oscillates.  But it's not caused by the charges decelerating as the hit the plates.  It's caused by the changing current (if it is changing) flowing into the plates.  Pfalstad 22:56, 5 October 2005 (UTC)

text: The displacement current that Maxwell defined does accompany propagating EM waves.  Pfalstad 22:56, 5 October 2005 (UTC)

text: Pfalstad - tag, your it.  LC - why don't you two go at it for awhile.  I have some work to do to get a house ready for resale so I'll be preoccupied for the near term.  Alfred Centauri 23:13, 5 October 2005 (UTC)
thread_title:  Pre 7 Oct 2005 posts 

message: It says the main reason for using oil in old large capacitors and transformers is because of the heat generated. Funny, I thought it was used mainly as an insulating medium and dielectric.--Light current 02:38, 20 September 2005 (UTC)
replies: text: see for example, the functions of transformer oil with the capacitor oil. to clarfy the use of oil in a capacitor.--Davy Jones 00:45, 12 October 2005 (UTC)
thread_title:  What's that Oil for again? 

message: I think this page is getting near to being good enough to be considered as a featured article. But is it too long for that. Any comments?--Light current 14:40, 5 October 2005 (UTC)
replies: text: Well, I think it needs just a little more work, which I have been doing. Snafflekid 06:18, 6 October 2005 (UTC)

text: Ack! Inductor is the bête noir! On my way. Snafflekid 06:36, 6 October 2005 (UTC)
replies: text: Wow! This would make a better Featured Talk page ;). --Davy Jones 12:48, 12 October 2005 (UTC)
thread_title:  Featured article 

message: Since I have now started the long awaited  (by some) page on Ivor Catt, I wonder if we should move all the discussions about Catt related subjects on this page to Talk:Ivor Catt. Could we have some comments please ASAP--Light current 14:05, 15 October 2005 (UTC)
replies: text: yes, we should  Pfalstad 21:25, 15 October 2005 (UTC)
replies: text: ye've got me :) --Davy Jones 06:56, 16 October 2005 (UTC)
thread_title:  Proposed move of some discussion material 

message: Do we need these pictures her or would they be better on the practical capacitors page? --Light current 01:25, 22 November 2005 (UTC)
thread_title:  Pictures 

message: In capacitors when newly electrons (of charge -Q) approaches one plate it will experience of force of repullsion from the negatively charged plate, and this increases their potential energy and the potential across the capacitor will increase
But as -Q approaches, -Q from the opp plate will get repelled (inducing a +Q on the plate),
The question now if this is happened shouldnt the potential of the capacitor becomes constant because as ΔPE comes from -Q on one plate shouldnt ΔPE is lost (or transferred) from the opp plate
----
--Ducky12345 (talk) 16:19, 2 March 2008 (UTC)
thread_title:  potential energy across capacitors 

message: When I'm logged in the images show up in the right place, but when logged out the images appear ontop of the text like in this screen shot of Capacitor.  There are blank spots in the text where the images are supposed to appear further down the page.  This is with Firefox 2.0 on osx.  Autopilot (talk) 01:39, 24 November 2008 (UTC)
replies: text: Looks ok to me in Firefox 3/XP.  I suggest that you take that one to WP:VPT, it is unlikely the editors of the article will be able to helo you. SpinningSpark 23:10, 14 December 2008 (UTC)
thread_title:  Formatting issues when not logged in? 

message: I mostly recall seeing \epsilon in textbooks but permittivity and this article use \varepsilon. Which do we prefer? I vote for the one which isn't a "variable" but I'm not really informed in these matters. Potatoswatter (talk) 02:21, 21 December 2008 (UTC)
replies: text: I don't think it matters, as long as we're consistent and we define the symbol; they're used pretty interchangeably.  I think the article's already internally consistent, so we should be OK. Papa November (talk) 02:33, 21 December 2008 (UTC)

text: Also, I'm not sure what you mean by a "variable" here.  Permittivity is generally a frequency dependent property so it can't be treated as an absolute constant. Papa November (talk) 02:36, 21 December 2008 (UTC)
replies: text:  Yes, but we don't have anywhere near that depth of treatment here. Neither do any textbooks I suppose I'd recall, (I seem to have lost my main E&M book :v( ) but permittivity does. Meh. Potatoswatter (talk) 06:00, 21 December 2008 (UTC)

text: FWIW, \varepsilon looks really fruity on my system (Firefox 3.6.x, Windows Vista x64 SP2). It is very thin and fey, sort of excessively cursive-looking.  A Scot might call it "twee". — SMcCandlish   Talk⇒ ʕ(Õلō)ˀ  Contribs. 06:48, 1 April 2010 (UTC)
thread_title:  Which epsilon symbol: ε or ϵ? 

message: The main article for microphony as an undesirable effect is microphonics (although it is not a very substantial article).  Condenser microphone is certainly the same physical effect but is not really in the context of non-ideal.  Do you want that changed? SpinningSpark 12:20, 21 December 2008 (UTC)
replies: text: Yes. Have at it. Binksternet (talk) 16:28, 21 December 2008 (UTC)

text: Thanks, sorry. Potatoswatter (talk) 04:08, 22 December 2008 (UTC)
thread_title:  Microphony 

message: There's a whole mess of other articles about capacitors. (Guess they're pretty sexy.) I think it would be a good idea to keep our eyes open and make sure they're all in the category. A number of them should be merged into electrolytic capacitor. Potatoswatter (talk) 04:08, 22 December 2008 (UTC)
thread_title:  Peripheral articles and [[:Category:Capacitors]] 

message: Uh, "The common parallel plate model reduces such a capacitor to a one-dimensional cross section." I know nothing about capacitors, but wouldn't two broad plates separated by a small distance be commonly modeled in two dimensions? (heck, the picture uses three). If the sentence is truly about a one-dimensional mathematical model, wouldn't it be better placed well before the intro of the concept of parallel plates? —Joel D. Reid (talk) 04:23, 27 December 2008 (UTC)
replies: text: Yes, I agree it was a little confusing.  I've rewritten it to avoid the discussion of dimensionality as it distracts the reader from the point (simple model, uniform field etc).  We need references still. Papa November (talk) 10:28, 27 December 2008 (UTC)
thread_title:  [[Capacitors#Parallel plate model]] 

message: Would the other editors taking part in this collaboration be agreeable to putting this article up for GA review.  I don't have a great deal of experience of this, but when I have been through it before the main things are that [1] you keep monitoring the review as it progresses so that problems are dealt with in a timely manner (otherwise the reviewer loses interest and goes away) and [2] absolutely everything has to be referenced, ie every para.  If you are all prepared to work on the article at this level I propose putting it up.
Also, I think the ESR section needs some work, the maths looks gastly.  A diagram would help to simplify it.  I will work on that bit if there are no objections. SpinningSpark 20:51, 5 January 2009 (UTC)
replies: text: No, it needs a lot more refs, and we haven't even touched much of the second half. Sorry I haven't continued to work on it, and I will be moving away and unable to work on next month's collaboration :v( . Yeah, ESR really needs a phasor diagram. Even when rewriting, it's hard for me to accomplish more than incremental improvement. Potatoswatter (talk) 22:21, 5 January 2009 (UTC)

text: I agree, we're nowhere near the correct level of referencing yet :(  I'm also pretty busy writing my thesis at the minute, so I'm out of action for a while, I'm afraid.  I'll get back to the article soon though! Papa November (talk) 22:34, 5 January 2009 (UTC)
thread_title:  GA review 

message: "Capacitors were discovered in glass jars in 1745 . . ."?  How about "The first form of capacitor was the Leyden jar, invented in 1745 . . ." --ChetvornoTALK 15:55, 29 January 2009 (UTC)
replies: text: Yeah, that edit isn't my best-ever material… very late night. I'm not sure whether Ewald Georg von Kleist's "Kliestian Jar" differs in some way from the Leyden jar, such as the addition of water inside. The other WP articles strongly imply they're exactly the same thing, but is there a good source for this? Potatoswatter (talk) 19:28, 29 January 2009 (UTC)
replies: text:  Indeed this is the case… confusing that nobody could repeat Kleist's experiment. Potatoswatter (talk) 19:39, 29 January 2009 (UTC)
thread_title:  Discovered in glass jars? 

message: Friends,
i am a HT consumer in india. in our montly billing our power factor is only 0.89. it has been advised by the electricity board people to add capacitors in our circuit. i wish to kno how the rating of the capacitor is arrived at and also how this has to be connected in the circuit.i heard that extra precautions need to be taken while switching on the Generator. i heard while switching on the circuit the capacitor needs to be disconnected.please throw some light on this.  —Preceding unsigned comment added by 59.90.213.170 (talk) 13:16, 11 March 2009 (UTC)
replies: text: This page is for discussing improvements to the article, not for discussion of the subject itself.  You might try Wikipedia:Reference desk/Science though, where the volunteers will try to answer any knowledge question. SpinningSpark 14:14, 11 March 2009 (UTC)
thread_title:  Connecting capacitors in a HT line 

message: In looking through electronic catalogs, I see that certain electrolytic capacitors are referred to as “Snap-In” capacitors, but I do not know what that means. Does it refer to a socket type - or what? An explanation would be appropriate for this article. I am sure that some thought could be give to expand this article to include definitions for many of the jargon words pertaining to capacitors.
Stan (talk) 18:00, 13 April 2009 (UTC)
replies: text: Snap-in refers to the lead type, which is preformed such that the capacitor holds itself in place when inserted in the pcb prior to soldering.  Traditional component leads require to be formed and cut prior to insertion, thus a manufacturing stage is saved.  I do not think it is particularly relevant to the article as this feature is not specific to capacitors and can be found on other components. SpinningSpark 22:48, 14 April 2009 (UTC)
thread_title:  Snap-in capacitors? 

message: In the last section:
Capacitors used in RF or sustained high-current applications can overheat,
What does RF stand for? A quick google search didn't turn up something useful. Perhaps someone can add it to the article. Thanks Panoramix303 (talk) 22:24, 22 May 2009 (UTC)
replies: text: wikilink added--Thorseth (talk) 06:38, 23 May 2009 (UTC)
replies: text:  Thanks Panoramix303 (talk) 11:36, 23 May 2009 (UTC)
thread_title:  Unknown abbreviation 

message: wat's difference between polarised and non-polarised capacitors and their functions?  —Preceding unsigned comment added by 115.99.0.27 (talk) 08:48, 29 June 2009 (UTC)
replies: text: A "polarized capacitor" probably refers to an electrolytic capacitor.  As it saya in the 'Dielectric' section, these use a liquid electrolyte.  They have much higher capacitance than other types, but have poor tolerances,  and high leakage current.  They are mainly used in power supplies, to filter (smooth) the DC output voltage.  The article omits the most important characteristic, which is that electrolytic capacitors can only have one polarity of voltage applied to them.  Their two leads are labelled with a (+) and a (-), and if a reverse voltage is applied, it will destroy them. --ChetvornoTALK 17:30, 29 June 2009 (UTC)

text: See electrolytic capacitor. An electrolyte is a conductive liquid solution. The electrolyte forms one terminal and oxidizes the surface of a piece of metal which forms the other terminal. The oxide is the dielectric. If you run current the wrong way, you get electron transfer leading to a redox chemical reaction which dissolves the metal terminal. So, polarized capacitors aren't fundamentally different in any way, they just have some electrochemical sensitivity. Potatoswatter (talk) 21:07, 29 June 2009 (UTC)
replies: text: Correct me if I'm wrong, but I was under the impression that the dielectric would be destroyed, rather than a metal terminal, if the wrong polarity of voltage is applied.  A similar effect can happen, albeit more slowly, if an electrolytic capacitor has no voltage applied over a period of years.  The oxide dielectric will gradually deteriorate, until the capacitor cannot withstand significant voltage and will short out if voltage is suddenly applied.  If you turn on an old piece of equipment which has been sitting unused for many years, it may pop and smoke may come out.  This is most commonly due to one or more electrolytic capacitors having insufficient dielectric remaining to withstand the suddenly applied voltage.  This is a topic which is briefly covered, but perhaps understated, in the Electrolytic capacitor article. Wildbear (talk) 07:21, 30 June 2009 (UTC)
replies: text: Everything gets destroyed if the metal is dissolved. The metal, the electrolyte, and the oxide layer. If the electrolyte is full of metal, it won't oxidize anything. Potatoswatter (talk) 19:46, 1 July 2009 (UTC)
thread_title:  Polarised vs. non-polarised capacitors? 

message: I made a photo of a variable capacitor made of 2 wires near each other in a frame:
300px
At least that's what I think this is supposed to be. Not sure, if another picture of a cap improves these articles, but this one clearly shows the "inside" of a cap. You may add it to the articles Capacitor, Types_of_capacitor and/or Variable_capacitor.
Should I trim the irrelevant stuff from this image?
:There's a lot of irrelevant stuff there, and that's not a common variable cap design. Apparently it's even unfamiliar to you… the one time I took apart a variable cap it had a stack of rotating semicircular plates. Potatoswatter (talk) 06:23, 9 July 2010 (UTC)
thread_title:  New variable capacitor image 

message: I am an educated person, though not in physics. (I took undergrad courses in physics & calculus ~15 years ago, but my PhD is in nutrition.)
I am now training as a volunteer at a large science museum where I live. I will be conducting demonstrations for tour and family groups (mostly kids), including a demonstration on static electricity. Part of the demonstration uses Leyden jars. In my search for more information about how Leyden jars work, I have been frustrated by technical articles describing ratios of charge to potential differences and such when what I really wanted to know was where the electrons went and how the charge was changed on the outer plate in response to the inner plate. Does the outer plate have to be grounded to allow the opposite charge to accumulate? Or is it a partial charge resulting from electron movement within the plate itself? What determines the voltage of an arc caused by touching the pole? Is it a simple matter of how many electrons are stored in one plate or the other? (I'm not looking for these answers on this talk page, just listing the kinds of questions I wanted to learn about in the article but had difficulty with. No need to respond directly to these questions here on the talk page.)
I just want you knowledgeable and talented physics and math people to know that this one guy (me) had a really difficult time learning what I wanted to know from this page, and I want to ask you all to consider presenting information here in a manner that might be more understandable to people like me who aren't that strong on our physics or calculus. I think a kid working on a transistor radio in shop class should be able to take away at least basic knowledge of how capacitors function. I appreciate the fact that all of this technical information is here for anyone who wants to learn the details, but please consider writing a basic description of the principles with us laypeople in mind -- maybe in its own section.
But please don't think of this as a harsh criticism. I truly do appreciate the work you've all done to bring an enormous amount of information to the Wikipedia knowledge base! Someday I might want to brush up on my physics & learn this stuff properly. Dcs002 (talk) 01:01, 10 October 2009 (UTC)
replies: text: This sort of specific constructive criticism is what all the electrotechnology article need and don't get. They get written by hobbyists, who have incomplete and eccentric notions of the subject and generally treat it in the most superficial fashion. Rarely an article gets visited by someone knowledgeable, who gets scared off when he gets overwritten by some teenager with time on his hands. Or, worse yet, some curmudgeon overturns an article based on his vast experience and knowledge, except that he can't write three consecutive clear sentences without diving into jargon. People who can write *well* get paid for doing it, and don't come here. There's an upper limit to the quality level of any Wikipedia electrotechnology article that is very low indeed.  Though I'm sure the articles on history, geography, mathematics, chemistry, etc. are in much better condition.... (from what I've read, the basics are, anyway.) Editing a Wikipedia article is a very good way to discover your own ignorance, as I have found.  --Wtshymanski (talk) 01:30, 10 October 2009 (UTC)
thread_title:  For less technical audiences?