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Something should be mentioned in this article about the Whistle effect that capacitors are known to make. Sabranan ( talk) 09:07, 24 June 2008 (UTC)
In a series Capacitive circuit
example:(12uF and 20uF in series with a 200V.d.c. supply)
Is the p.d. across each capacitor identical; even if the are of different values
or are the values of Vdrop across each capacitor =Q total/C of component.
--
SparxDaBear (
talk)
16:07, 24 March 2008 (UTC)
I'm starting to see motherboards cropping up advertising themselves as having "all solid capacitors" ... could someone tell me what type of capacitors these boards might be using and what the advantage of using these "solid capacitors" is? -- Pandora Xero ( talk) 18:17, 11 March 2008 (UTC)
please explain polarized cacitor chaging and discharging in ac
Some discussion of the distinction between real and ideal capacitors is needed in an encyclopaedic article. There should be at least a brief mention in the introduction; possibly details belong in a new section in the body? I state this hear as an addition I made was reverted; it is needed for a comprehensive article (I have reinstated my version for now).. Pol098 ( talk) 16:47, 31 July 2008 (UTC)
26-Sep-2008: The first time reading the article "Capacitor" there was no indication that capacitors come in a "wide variety" of types and sizes: the typical small electrolytic capacitors were shown in the top photo. However, I learned, days later, about several larger and mechanical types of capacitors. To help the article be more inclusive ("encyclo-"), I have added a short sentence about the "wide variety" and mentioned the added images of other capacitors. With the new text and images, hopefully, other readers will quickly see that a broad array of capacitors have been developed, and not imagine that the photo of small electronic capacitors represents the full range of capacitors. It is a balancing act: to show some of the broad variety/range, without cluttering the article with dozens of photos of capacitor types. - Wikid77 ( talk) 04:27, 26 September 2008 (UTC)
The article indicates, understandably, that a capacitor has a useful life during which its ability to store energy degrades over time. Is there a period of time over which this degradation occurs that can be described in the article? (i.e., years, hours of use, etc.) Ilikehifi ( talk) 19:45, 26 September 2008 (UTC)
If anyone knows exactly what we need to learn for HIGCSE Science please do tell us... Its difficult and confusing and we write tomorrow and I'm stressed! (yes I sound like a moron but I'm working on very few hours sleep and cried after my 1st test) —Preceding unsigned comment added by 41.243.133.38 ( talk) 17:27, 6 October 2008 (UTC)
A capacitor or condenser is a passive electronic component consisting of a pair of conductors separated by a dielectric. When a voltage potential difference exists between the conductors, an electric field is present in the dielectric. This field stores energy and produces a mechanical force between the plates. The effect is greatest between wide, flat, parallel, narrowly separated conductors.
I edited the article to remove nF and mF units because I can't find where they are used in actual capacitors, and mF is a unit that is particularly subject to confusion. I didn't make this stuff up – it's common practice in electronics, consistent with my own (admittedly American) experience. I know I've made this argument before, and listed distributor and manufacturer sites that agree, but can't seem to find it at the moment. I'll note that one of the reverted edits was the caption of an image showing a capacitor marked "10,000 μF". I simply made the caption match the picture. Why shouldn't it? Can someone provide pics of actual physical capacitors that are marked in nF or mF? (pinging @ Piguy101 and Indrek) —[ AlanM1( talk)]— 21:32, 18 July 2014 (UTC)
mFto
millifarads (mF)? Would you find that satisfactory?
I am pretty sure that the capacitor in the second picture is actually 4.7uF, as a 4.7 millifarad capacitor would be much larger than the one next to it.I'm not so sure. For one, the capacitor next to it seems to be 47 μF, so it seems reasonable for the yellow one to be in the millifarad range. And secondly, the physical size of a capacitor can't really be used to estimate its capacitance. For instance, I have a 0.1 F (100 mF) cap in my parts drawer that's about the size of an LR44 battery, and dwarfed by some 100 μF capacitors. Other characteristics like working voltage can influence a capacitor's size more than its capacitance.
millifarads should not be in the article. This is simply because it is not standard usage (I have no idea why, though).Well, as I mentioned on my talk page, it's possibly because most capacitors are in the microfarad range and below. Gigaohm resistors are also pretty rare, but that doesn't mean that unit shouldn't be used when appropriate (i.e. when describing a resistor with sufficiently large resistance). I'd still like to hear an actual problem with using millifarads. Indrek ( talk) 07:10, 19 July 2014 (UTC)
The following electronics texts mention neither nanofarads nor millifarads in their capacitance sections. There are many more. I tried to select a variety of dates and countries of publication (U.S., U.K., India so far):
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help)There are other sources that mention nF and mF secondarily (i.e. as unusual or not customary), which I think is a better solution, given that we now see that they seem to exist on at least one physical capacitor. I believe due weight would be a line or two about nF and mF and that they are not commonly used. Unless we can find a consistent reason that's citable, I'd leave out any mention of reason.
I see no reason to caption anything other than 10,000 μF for the picture – that's how it's marked and anything else is technically WP:OR or WP:SYNTH, right? If it were marked with a code (like 100? I don't know how 1.0×1010pF is supposed to be represented, or is that the upper limit for the A.B×10C coding?), I would understand wanting to translate it to a human-readable form, like translating "103" to 10,000 pF or 0.01 μF. But that's not the case here. It's marked 10,000 μF because that's the value in customary units.
Personally, in my decades of (admittedly U.S.) training and experience in design and repair of component-level electronics, from consumer audio to communications, I can't recall seeing or using nF or mF. I worked on equipment made in the U.S., Canada, east Asia, and Europe. I mention this only to show that I'm not just blindly reading the sources – they are consistent with my own experience. —[ AlanM1( talk)]— 08:37, 20 July 2014 (UTC)
I believe due weight would be a line or two about nF and mF and that they are not commonly used.The issue at hand isn't the prevalence (or rarity) of certain prefixes on components or in technical literature, that's already covered in Farad. The issue here is one of style - whether or not text on Wikipedia related to capacitors and capacitance should avoid certain prefixes. Like in the sentence "Typical capacitance values range from about 1 pF to about 1 mF.", which you changed to "Typical capacitance values range from about 1 pF to about 1000 μF." (emphasis mine). I believe this sort of change is unconstructive, because it runs counter to the main point of the SI prefixes (to keep numeric values as readable as possible by avoiding long leading or trailing zeroes), and doesn't actually improve the article in any way, as there seems to be no evidence that someone might misread "1 mF" as meaning "one microfarad" instead of "one millifarad". Perhaps in the past when non-standard abbreviations for microfarad were common that might have been a legitimate concern, but surely not anymore?
I see no reason to caption anything other than 10,000 μF for the picture – that's how it's marked and anything else is technically WP:OR or WP:SYNTH, right?Converting units is not OR, per WP:CALC. As for a reason, how about legibility? The same reason that, for instance, this image is captioned "A 2-meter carpenter's rule", even though the numeric markings on it are in centimetres - it's easier to read that way. Just like "10 mF" is easier to read than "10000 μF". Frankly, I see no reason to caption the image anything other than "10 mF", but I guess I can see the remote possibility that some readers might not immediately make the connection between the caption and the markings on the component; hence why Piguy101's suggestion above seems like a reasonable compromise.
The fact that there are many texts that specifically avoid mention of nF and/or mF, and others that mention that they are not routinely used, is more telling than the ones that do mention those units without comment.I disagree. The texts that "specifically avoid" the nanofarad are almost exclusively US ones. As for the millifarad, I've already explained why I think it's less common in technical literature - because many texts probably don't deal with capacitors significantly in the millifarad range. That doesn't mean they "specifically avoid" the unit, it's just that it's not needed as often as the smaller units. Kind of like microbiology textbooks probably don't need to use the kilometre very often.
"Deca-ohm" (or decohm?) and "centi-farad" are "standard SI" prefixes and units, but those aren't used either, despite being in the range of physically useful values.The MOS specifically recommends against the use of the centi-, deci-, deca- and hecto- prefixes, so that's a moot point.
Convention is what it isYes, and the convention clearly isn't to completely avoid nanofarads and millifarads. As we've established, they're used in technical literature as well as in component markings.
I contend people will routinely stumble over "1 mF" and "1 nF" because they are unfamiliar units to most. It's not that they can't figure out (hopefully) that 1 mF is 1000 μF – it's just that it looks "weird".Sorry, but I can't believe for a second that "routinely" is the applicable word here. "Very occasionally", perhaps. If you know that the "m" stands for one thousandth and that the "F" stands for farad, you know what "mF" means. And if you don't know what the "m" stands for, you're also going stumble over millimetres or milliseconds. That's the beauty of the SI system - each prefix always means the same thing regardless of the unit it's affixed to. It may perhaps take a fraction of a second to shift the decimal point by three places if you're not used to millifarads or nanofarads, but to actually "stumble" over it, to the point where it impedes your understanding the article? Highly unlikely.
If you don't like using the prevalence of literature, how about a count of manufacturers that don't use nF or mF compared to those who do? I predict at least 5:1 don't.Here's the thing (which I've already mentioned above, but apparently not with sufficient emphasis). The Wikipedia Manual of Style is not necessarily based on how things are written elsewhere. For instance, a lot of technical literature doesn't put a space between the number and the unit, yet the MOS requires that we do. Component markings and printed literature, both of which can date back several decades, have requirements and constraints that a digital encyclopaedia in the 21st century is not necessarily subject to. We don't need to cater to people who still think "MFD" is a valid abbreviation for microfarad, or who don't know what a picofarad is unless it's pronounced "puff". We don't need to worry about whether the "μ" symbol is available, whether "m" and "n" will look sufficiently different in a schematic after it's been copied a dozen times, or whatever other concerns were relevant 20-30 years ago.
I started to respond point by point, but I don't see getting past what appears to be an WP:ENGVAR-type problem.Which is why I'll recommend again that we not get bogged down with component markings, decades-old literature and recommendations from random websites, and instead try to figure out whether there is even an actual problem here that needs to be solved, and if there is, whether banning nano- and millifarads is really a better solution than the alternatives that have been suggested above.
I think less astonishment occurs to a reader used to seeing 10 nF seeing 0.01 μF than a reader that is used to seeing 0.01 μF seeing 10 nF, because μF is the more common unit.Fair point, but that principle only applies when there is a significant chance of astonishment from either option. In other words, it's only relevant when the assumption that people are likely to not understand what "nF" means when reading capacitance-related articles on Wikipedia is true. So far, no evidece that would support such an assumption has been produced.
I really don't see any support for using mF.Come again? I've very clearly expressed support for using mF. @ Piguy101 has, at the very least, expressed tentative support. There's also the implicit consensus for using milli- and nanofarads, based on the fact that whatever edits added those units have gone uncontested until now.
I am surprised that the conversation has attracted so little attention, and would welcome a wider audience. Perhaps an RfC?I agree that input from more editors would be beneficial. An RfC is a good idea, but since this is a style issue that affects multiple articles, perhaps we should move the discussion to the relevant MOS talk page (as I suggested on my talk page)? Indrek ( talk) 12:54, 22 July 2014 (UTC)
As an author of many capacitor articles I aggree with Alan to remove mF (Millifarad). In the capacitor industry it is unusable to write "mF", on the insulation of big screw terminal aluminum electrolytic capacitors of todays production is written "µF" to avoid misunderstandings.
"nF" (Nanofarad) is often used for class 1 ceramic capacitors. -- Elcap ( talk) 07:50, 21 July 2014 (UTC)
To behoove readers, I am listing the general opinion of each of the editors so far. Feel free to adjust your own. Piguy101 ( talk) 18:44, 22 July 2014 (UTC)
@ AlanM1, Indrek, Elcap, and Zaereth and others: Since no one has posted in about a week, can I (or someone else) close this discussion and add a note at the top of the talkpage, explaining the censensus using {{ Consensus}}? The note could read something like: The consensus for the prefixes before farad is that all SI prefixes are acceptable, but the first instance of each prefix should include the numbers without the prefix as well. For photos of capacitors, captions should read as the units seen in the photo to prevent confusion. Piguy101 ( talk) 18:06, 31 July 2014 (UTC)
I'm afraid I don't see a consensus here, especially not "that all SI prefixes are acceptable" (centifarads, decifarads, decafarads?). Here's a chart of the opinions of the five respondents on the issues at hand, as I understand the summaries above. The meanings are:
User | nF | mF |
---|---|---|
AlanM1 | M | M |
Indrek | U | U |
Piguy101 | U | A |
Elcap | U | A |
Zaereth | ? | ? |
—[ AlanM1( talk)]— 23:44, 31 July 2014 (UTC)
I'm afraid I don't see a consensus hereFrom WP:CON: "Consensus on Wikipedia does not mean unanimity ... nor is it the result of a vote". In other words, it's possible for consensus to be reached even when editors are still technically in disagreement. But I'm sure you knew that already.
mF can get confused with uF, as I mentioned above.Is there any actual evidence of this confusion, specifically as pertaining to Wikipedia? So far, none has been provided. Also, Wikipedia doesn't use the non-standard "uF" (or if it does, it should be corrected to "μF" anyway). Indrek ( talk) 05:49, 1 August 2014 (UTC)
I would like to note that there is only one use of millifarad in the entire article.That's true, but there are also other capacitance-related articles on Wikipedia, and whatever consensus we achieve here will apply them as well. I don't think the debate is silly, but I am starting to feel frustrated by the lack of progress.
I was asked for a source, so I provided one.Actually, you were asked for evidence. Specifically, evidence that people reading Wikipedia are being confused by the use of the "mF" abbreviation. Not speculation about why "mF" might be uncommon in component markings, decades-old printed literature, or whatever. I apologise if my request was not clear enough, but I feel like I've repeated it enough times that it should deserve to be addressed properly.
And please, there is no need to repeat to me what I said. I am aware of what I wrote.I was merely specifying which part of your post I was responding to. No reason to be offended, this is standard practice on talk pages. Indrek ( talk) 06:42, 2 August 2014 (UTC)
Since we all agree that this is getting nowhere, how about putting in an RfC? Piguy101 ( talk) 21:12, 1 August 2014 (UTC)
Holy crap. You guys wasted all that hot air on mF and nF when you could have actually been improving articles? Well, there's a good 1000 man-hours worth of labor no one will ever get back. No wonder productivity in industrial countries is stagnating. -- Chetvorno TALK 22:17, 25 September 2014 (UTC)
The introduction to the Leyden Jar meme mentions an earlier form of large insulated condensor, but you start the history on the broader capacitor meme which should cover that at the Leyden jar. Could you contact the original author of the Leyden jar meme to find out what he means and add it here, please? — Preceding unsigned comment added by 94.10.227.199 ( talk) 01:25, 17 January 2015 (UTC)
Henry_Cavendish#Electrical_research says "among Cavendish's discoveries were ... an early unit of capacitance (that of a sphere one inch in diameter), the formula for the capacitance of a plate capacitor,[25] the concept of the dielectric constant of a material" ? - Rod57 ( talk) 02:16, 30 November 2015 (UTC)
A Franklin square was a type of early capacitor invented by Benjamin Franklin. [1] and used to explain the operation of the Leyden jar. - Rod57 ( talk) 03:00, 1 December 2015 (UTC)
References
Which setup produces higher voltage and which produces higher current, or both? Series or parallel? That is information that should be stated more clearly in the article. ZFT ( talk) 01:10, 6 August 2016 (UTC)
Until recently the lead sentence read:
Recently an editor removed the word "temporarily" from this sentence. He gave his reason as: Capacitors can store charge for a long time. They are not batteries but they do not bleed off their charge quickly. It can be dangerous to think energy is stored temporarily.
I think the word should be put back. This is an example of how Wikipedia technical leads become unintelligible. Without the word "temporarily", nontechnical readers are going to get the idea a capacitor is like a rechargeable battery, serving as a long-term power source for electrical devices. Only a few capacitors ( supercapacitors) have that function. In most applications, capacitors store energy for a tiny fraction of a second, during part of a cycle of alternating current, and return the energy immediately. The article already has a section on Hazards and safety. The idea that the word "temporarily" in the sentence will make people reckless with capacitors is ridiculous. -- Chetvorno TALK 02:07, 29 August 2016 (UTC)
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Thank you, the author(s) of this article. We translated your article into the Tatar language.-- A.Khamidullin ( talk) 12:34, 26 March 2017 (UTC)
Displacement is being used incorrectly in the third paragraph of the lede. Displacement current only occurs inside the capacitor. There is no displacement current in the source circuit or the battery. There is conduction current in the source circuit that is equal to the displacement current in the capacitor, so it is not egregiously incorrect. But, the notion of displacement current is not displacement through the external circuit. It is the displacement of bound charges in the dielectric from their equilibrium position. In the case of a high permittivity dielectric, it is easy to visualize the electron orbitals slightly distorted such that the electrons spend more time on one side of their molecules compared to the orbital with no applied field. In the case of a vacuum, it is harder to visualize. In Maxwell’s time, the vacuum was thought to be a polarizable media just like any other dielectric. But no matter how hard it is to visualize, the displacement current occurs between the plates of the capacitor and not in the battery. Constant314 ( talk) 20:25, 11 April 2017 (UTC)
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Recent deletions from the bibliography left some dangling references. Unfortunately this article uses two reference styles. One of the styles only gives a partial reference, often giving the last name and year only. These type references depend on a full reference in the bibliography to complete the entry. Notably, refence to Dorf and Ulaby are of this type. Perhaps others. Constant314 ( talk) 01:04, 17 November 2019 (UTC)
Thanks for the convincing arguments! I have to revise my opinion. Sorry for reacting in this form. I still don't know how to talk on Wikipedia :-) Is it just by Editing the source? — Preceding unsigned comment added by Koitus~nlwiki ( talk • contribs) 23:21, 24 February 2021 (UTC)
An electric field in a capacitor does NOT contain energy. The energy of a capacitor is in the electrons on the plates. In loading a capacitor a battery does work on the electrons (not on some field). The electric field is only the result of a created potential difference. So yes, a capacitor contains energy, but not its field but its electrons. Please, change the first sentence of this article. By the way, for a parallel-plate capacitor the E-field does NOT depend on z. Therefore, the equation is not consistent with the text. So change the equation too, please. — Preceding unsigned comment added by Koitus~nlwiki ( talk • contribs) 15:59, 24 February 2021 (UTC)
What type of capacitor do I need? I'm running a 120v generator that seems to have a voltage drop when the refrigerator comes on. This causes my stereo to shut off (automatic surge protection). I would like to end this problem. Thank you. 2001:5B0:4FDE:AE98:ADBD:2F77:5C4B:BAEF ( talk) 16:40, 4 February 2022 (UTC)
![]() | 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. |
Archive 1 | Archive 2 | Archive 3 | Archive 4 |
Something should be mentioned in this article about the Whistle effect that capacitors are known to make. Sabranan ( talk) 09:07, 24 June 2008 (UTC)
In a series Capacitive circuit
example:(12uF and 20uF in series with a 200V.d.c. supply)
Is the p.d. across each capacitor identical; even if the are of different values
or are the values of Vdrop across each capacitor =Q total/C of component.
--
SparxDaBear (
talk)
16:07, 24 March 2008 (UTC)
I'm starting to see motherboards cropping up advertising themselves as having "all solid capacitors" ... could someone tell me what type of capacitors these boards might be using and what the advantage of using these "solid capacitors" is? -- Pandora Xero ( talk) 18:17, 11 March 2008 (UTC)
please explain polarized cacitor chaging and discharging in ac
Some discussion of the distinction between real and ideal capacitors is needed in an encyclopaedic article. There should be at least a brief mention in the introduction; possibly details belong in a new section in the body? I state this hear as an addition I made was reverted; it is needed for a comprehensive article (I have reinstated my version for now).. Pol098 ( talk) 16:47, 31 July 2008 (UTC)
26-Sep-2008: The first time reading the article "Capacitor" there was no indication that capacitors come in a "wide variety" of types and sizes: the typical small electrolytic capacitors were shown in the top photo. However, I learned, days later, about several larger and mechanical types of capacitors. To help the article be more inclusive ("encyclo-"), I have added a short sentence about the "wide variety" and mentioned the added images of other capacitors. With the new text and images, hopefully, other readers will quickly see that a broad array of capacitors have been developed, and not imagine that the photo of small electronic capacitors represents the full range of capacitors. It is a balancing act: to show some of the broad variety/range, without cluttering the article with dozens of photos of capacitor types. - Wikid77 ( talk) 04:27, 26 September 2008 (UTC)
The article indicates, understandably, that a capacitor has a useful life during which its ability to store energy degrades over time. Is there a period of time over which this degradation occurs that can be described in the article? (i.e., years, hours of use, etc.) Ilikehifi ( talk) 19:45, 26 September 2008 (UTC)
If anyone knows exactly what we need to learn for HIGCSE Science please do tell us... Its difficult and confusing and we write tomorrow and I'm stressed! (yes I sound like a moron but I'm working on very few hours sleep and cried after my 1st test) —Preceding unsigned comment added by 41.243.133.38 ( talk) 17:27, 6 October 2008 (UTC)
A capacitor or condenser is a passive electronic component consisting of a pair of conductors separated by a dielectric. When a voltage potential difference exists between the conductors, an electric field is present in the dielectric. This field stores energy and produces a mechanical force between the plates. The effect is greatest between wide, flat, parallel, narrowly separated conductors.
I edited the article to remove nF and mF units because I can't find where they are used in actual capacitors, and mF is a unit that is particularly subject to confusion. I didn't make this stuff up – it's common practice in electronics, consistent with my own (admittedly American) experience. I know I've made this argument before, and listed distributor and manufacturer sites that agree, but can't seem to find it at the moment. I'll note that one of the reverted edits was the caption of an image showing a capacitor marked "10,000 μF". I simply made the caption match the picture. Why shouldn't it? Can someone provide pics of actual physical capacitors that are marked in nF or mF? (pinging @ Piguy101 and Indrek) —[ AlanM1( talk)]— 21:32, 18 July 2014 (UTC)
mFto
millifarads (mF)? Would you find that satisfactory?
I am pretty sure that the capacitor in the second picture is actually 4.7uF, as a 4.7 millifarad capacitor would be much larger than the one next to it.I'm not so sure. For one, the capacitor next to it seems to be 47 μF, so it seems reasonable for the yellow one to be in the millifarad range. And secondly, the physical size of a capacitor can't really be used to estimate its capacitance. For instance, I have a 0.1 F (100 mF) cap in my parts drawer that's about the size of an LR44 battery, and dwarfed by some 100 μF capacitors. Other characteristics like working voltage can influence a capacitor's size more than its capacitance.
millifarads should not be in the article. This is simply because it is not standard usage (I have no idea why, though).Well, as I mentioned on my talk page, it's possibly because most capacitors are in the microfarad range and below. Gigaohm resistors are also pretty rare, but that doesn't mean that unit shouldn't be used when appropriate (i.e. when describing a resistor with sufficiently large resistance). I'd still like to hear an actual problem with using millifarads. Indrek ( talk) 07:10, 19 July 2014 (UTC)
The following electronics texts mention neither nanofarads nor millifarads in their capacitance sections. There are many more. I tried to select a variety of dates and countries of publication (U.S., U.K., India so far):
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help)There are other sources that mention nF and mF secondarily (i.e. as unusual or not customary), which I think is a better solution, given that we now see that they seem to exist on at least one physical capacitor. I believe due weight would be a line or two about nF and mF and that they are not commonly used. Unless we can find a consistent reason that's citable, I'd leave out any mention of reason.
I see no reason to caption anything other than 10,000 μF for the picture – that's how it's marked and anything else is technically WP:OR or WP:SYNTH, right? If it were marked with a code (like 100? I don't know how 1.0×1010pF is supposed to be represented, or is that the upper limit for the A.B×10C coding?), I would understand wanting to translate it to a human-readable form, like translating "103" to 10,000 pF or 0.01 μF. But that's not the case here. It's marked 10,000 μF because that's the value in customary units.
Personally, in my decades of (admittedly U.S.) training and experience in design and repair of component-level electronics, from consumer audio to communications, I can't recall seeing or using nF or mF. I worked on equipment made in the U.S., Canada, east Asia, and Europe. I mention this only to show that I'm not just blindly reading the sources – they are consistent with my own experience. —[ AlanM1( talk)]— 08:37, 20 July 2014 (UTC)
I believe due weight would be a line or two about nF and mF and that they are not commonly used.The issue at hand isn't the prevalence (or rarity) of certain prefixes on components or in technical literature, that's already covered in Farad. The issue here is one of style - whether or not text on Wikipedia related to capacitors and capacitance should avoid certain prefixes. Like in the sentence "Typical capacitance values range from about 1 pF to about 1 mF.", which you changed to "Typical capacitance values range from about 1 pF to about 1000 μF." (emphasis mine). I believe this sort of change is unconstructive, because it runs counter to the main point of the SI prefixes (to keep numeric values as readable as possible by avoiding long leading or trailing zeroes), and doesn't actually improve the article in any way, as there seems to be no evidence that someone might misread "1 mF" as meaning "one microfarad" instead of "one millifarad". Perhaps in the past when non-standard abbreviations for microfarad were common that might have been a legitimate concern, but surely not anymore?
I see no reason to caption anything other than 10,000 μF for the picture – that's how it's marked and anything else is technically WP:OR or WP:SYNTH, right?Converting units is not OR, per WP:CALC. As for a reason, how about legibility? The same reason that, for instance, this image is captioned "A 2-meter carpenter's rule", even though the numeric markings on it are in centimetres - it's easier to read that way. Just like "10 mF" is easier to read than "10000 μF". Frankly, I see no reason to caption the image anything other than "10 mF", but I guess I can see the remote possibility that some readers might not immediately make the connection between the caption and the markings on the component; hence why Piguy101's suggestion above seems like a reasonable compromise.
The fact that there are many texts that specifically avoid mention of nF and/or mF, and others that mention that they are not routinely used, is more telling than the ones that do mention those units without comment.I disagree. The texts that "specifically avoid" the nanofarad are almost exclusively US ones. As for the millifarad, I've already explained why I think it's less common in technical literature - because many texts probably don't deal with capacitors significantly in the millifarad range. That doesn't mean they "specifically avoid" the unit, it's just that it's not needed as often as the smaller units. Kind of like microbiology textbooks probably don't need to use the kilometre very often.
"Deca-ohm" (or decohm?) and "centi-farad" are "standard SI" prefixes and units, but those aren't used either, despite being in the range of physically useful values.The MOS specifically recommends against the use of the centi-, deci-, deca- and hecto- prefixes, so that's a moot point.
Convention is what it isYes, and the convention clearly isn't to completely avoid nanofarads and millifarads. As we've established, they're used in technical literature as well as in component markings.
I contend people will routinely stumble over "1 mF" and "1 nF" because they are unfamiliar units to most. It's not that they can't figure out (hopefully) that 1 mF is 1000 μF – it's just that it looks "weird".Sorry, but I can't believe for a second that "routinely" is the applicable word here. "Very occasionally", perhaps. If you know that the "m" stands for one thousandth and that the "F" stands for farad, you know what "mF" means. And if you don't know what the "m" stands for, you're also going stumble over millimetres or milliseconds. That's the beauty of the SI system - each prefix always means the same thing regardless of the unit it's affixed to. It may perhaps take a fraction of a second to shift the decimal point by three places if you're not used to millifarads or nanofarads, but to actually "stumble" over it, to the point where it impedes your understanding the article? Highly unlikely.
If you don't like using the prevalence of literature, how about a count of manufacturers that don't use nF or mF compared to those who do? I predict at least 5:1 don't.Here's the thing (which I've already mentioned above, but apparently not with sufficient emphasis). The Wikipedia Manual of Style is not necessarily based on how things are written elsewhere. For instance, a lot of technical literature doesn't put a space between the number and the unit, yet the MOS requires that we do. Component markings and printed literature, both of which can date back several decades, have requirements and constraints that a digital encyclopaedia in the 21st century is not necessarily subject to. We don't need to cater to people who still think "MFD" is a valid abbreviation for microfarad, or who don't know what a picofarad is unless it's pronounced "puff". We don't need to worry about whether the "μ" symbol is available, whether "m" and "n" will look sufficiently different in a schematic after it's been copied a dozen times, or whatever other concerns were relevant 20-30 years ago.
I started to respond point by point, but I don't see getting past what appears to be an WP:ENGVAR-type problem.Which is why I'll recommend again that we not get bogged down with component markings, decades-old literature and recommendations from random websites, and instead try to figure out whether there is even an actual problem here that needs to be solved, and if there is, whether banning nano- and millifarads is really a better solution than the alternatives that have been suggested above.
I think less astonishment occurs to a reader used to seeing 10 nF seeing 0.01 μF than a reader that is used to seeing 0.01 μF seeing 10 nF, because μF is the more common unit.Fair point, but that principle only applies when there is a significant chance of astonishment from either option. In other words, it's only relevant when the assumption that people are likely to not understand what "nF" means when reading capacitance-related articles on Wikipedia is true. So far, no evidece that would support such an assumption has been produced.
I really don't see any support for using mF.Come again? I've very clearly expressed support for using mF. @ Piguy101 has, at the very least, expressed tentative support. There's also the implicit consensus for using milli- and nanofarads, based on the fact that whatever edits added those units have gone uncontested until now.
I am surprised that the conversation has attracted so little attention, and would welcome a wider audience. Perhaps an RfC?I agree that input from more editors would be beneficial. An RfC is a good idea, but since this is a style issue that affects multiple articles, perhaps we should move the discussion to the relevant MOS talk page (as I suggested on my talk page)? Indrek ( talk) 12:54, 22 July 2014 (UTC)
As an author of many capacitor articles I aggree with Alan to remove mF (Millifarad). In the capacitor industry it is unusable to write "mF", on the insulation of big screw terminal aluminum electrolytic capacitors of todays production is written "µF" to avoid misunderstandings.
"nF" (Nanofarad) is often used for class 1 ceramic capacitors. -- Elcap ( talk) 07:50, 21 July 2014 (UTC)
To behoove readers, I am listing the general opinion of each of the editors so far. Feel free to adjust your own. Piguy101 ( talk) 18:44, 22 July 2014 (UTC)
@ AlanM1, Indrek, Elcap, and Zaereth and others: Since no one has posted in about a week, can I (or someone else) close this discussion and add a note at the top of the talkpage, explaining the censensus using {{ Consensus}}? The note could read something like: The consensus for the prefixes before farad is that all SI prefixes are acceptable, but the first instance of each prefix should include the numbers without the prefix as well. For photos of capacitors, captions should read as the units seen in the photo to prevent confusion. Piguy101 ( talk) 18:06, 31 July 2014 (UTC)
I'm afraid I don't see a consensus here, especially not "that all SI prefixes are acceptable" (centifarads, decifarads, decafarads?). Here's a chart of the opinions of the five respondents on the issues at hand, as I understand the summaries above. The meanings are:
User | nF | mF |
---|---|---|
AlanM1 | M | M |
Indrek | U | U |
Piguy101 | U | A |
Elcap | U | A |
Zaereth | ? | ? |
—[ AlanM1( talk)]— 23:44, 31 July 2014 (UTC)
I'm afraid I don't see a consensus hereFrom WP:CON: "Consensus on Wikipedia does not mean unanimity ... nor is it the result of a vote". In other words, it's possible for consensus to be reached even when editors are still technically in disagreement. But I'm sure you knew that already.
mF can get confused with uF, as I mentioned above.Is there any actual evidence of this confusion, specifically as pertaining to Wikipedia? So far, none has been provided. Also, Wikipedia doesn't use the non-standard "uF" (or if it does, it should be corrected to "μF" anyway). Indrek ( talk) 05:49, 1 August 2014 (UTC)
I would like to note that there is only one use of millifarad in the entire article.That's true, but there are also other capacitance-related articles on Wikipedia, and whatever consensus we achieve here will apply them as well. I don't think the debate is silly, but I am starting to feel frustrated by the lack of progress.
I was asked for a source, so I provided one.Actually, you were asked for evidence. Specifically, evidence that people reading Wikipedia are being confused by the use of the "mF" abbreviation. Not speculation about why "mF" might be uncommon in component markings, decades-old printed literature, or whatever. I apologise if my request was not clear enough, but I feel like I've repeated it enough times that it should deserve to be addressed properly.
And please, there is no need to repeat to me what I said. I am aware of what I wrote.I was merely specifying which part of your post I was responding to. No reason to be offended, this is standard practice on talk pages. Indrek ( talk) 06:42, 2 August 2014 (UTC)
Since we all agree that this is getting nowhere, how about putting in an RfC? Piguy101 ( talk) 21:12, 1 August 2014 (UTC)
Holy crap. You guys wasted all that hot air on mF and nF when you could have actually been improving articles? Well, there's a good 1000 man-hours worth of labor no one will ever get back. No wonder productivity in industrial countries is stagnating. -- Chetvorno TALK 22:17, 25 September 2014 (UTC)
The introduction to the Leyden Jar meme mentions an earlier form of large insulated condensor, but you start the history on the broader capacitor meme which should cover that at the Leyden jar. Could you contact the original author of the Leyden jar meme to find out what he means and add it here, please? — Preceding unsigned comment added by 94.10.227.199 ( talk) 01:25, 17 January 2015 (UTC)
Henry_Cavendish#Electrical_research says "among Cavendish's discoveries were ... an early unit of capacitance (that of a sphere one inch in diameter), the formula for the capacitance of a plate capacitor,[25] the concept of the dielectric constant of a material" ? - Rod57 ( talk) 02:16, 30 November 2015 (UTC)
A Franklin square was a type of early capacitor invented by Benjamin Franklin. [1] and used to explain the operation of the Leyden jar. - Rod57 ( talk) 03:00, 1 December 2015 (UTC)
References
Which setup produces higher voltage and which produces higher current, or both? Series or parallel? That is information that should be stated more clearly in the article. ZFT ( talk) 01:10, 6 August 2016 (UTC)
Until recently the lead sentence read:
Recently an editor removed the word "temporarily" from this sentence. He gave his reason as: Capacitors can store charge for a long time. They are not batteries but they do not bleed off their charge quickly. It can be dangerous to think energy is stored temporarily.
I think the word should be put back. This is an example of how Wikipedia technical leads become unintelligible. Without the word "temporarily", nontechnical readers are going to get the idea a capacitor is like a rechargeable battery, serving as a long-term power source for electrical devices. Only a few capacitors ( supercapacitors) have that function. In most applications, capacitors store energy for a tiny fraction of a second, during part of a cycle of alternating current, and return the energy immediately. The article already has a section on Hazards and safety. The idea that the word "temporarily" in the sentence will make people reckless with capacitors is ridiculous. -- Chetvorno TALK 02:07, 29 August 2016 (UTC)
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Thank you, the author(s) of this article. We translated your article into the Tatar language.-- A.Khamidullin ( talk) 12:34, 26 March 2017 (UTC)
Displacement is being used incorrectly in the third paragraph of the lede. Displacement current only occurs inside the capacitor. There is no displacement current in the source circuit or the battery. There is conduction current in the source circuit that is equal to the displacement current in the capacitor, so it is not egregiously incorrect. But, the notion of displacement current is not displacement through the external circuit. It is the displacement of bound charges in the dielectric from their equilibrium position. In the case of a high permittivity dielectric, it is easy to visualize the electron orbitals slightly distorted such that the electrons spend more time on one side of their molecules compared to the orbital with no applied field. In the case of a vacuum, it is harder to visualize. In Maxwell’s time, the vacuum was thought to be a polarizable media just like any other dielectric. But no matter how hard it is to visualize, the displacement current occurs between the plates of the capacitor and not in the battery. Constant314 ( talk) 20:25, 11 April 2017 (UTC)
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Recent deletions from the bibliography left some dangling references. Unfortunately this article uses two reference styles. One of the styles only gives a partial reference, often giving the last name and year only. These type references depend on a full reference in the bibliography to complete the entry. Notably, refence to Dorf and Ulaby are of this type. Perhaps others. Constant314 ( talk) 01:04, 17 November 2019 (UTC)
Thanks for the convincing arguments! I have to revise my opinion. Sorry for reacting in this form. I still don't know how to talk on Wikipedia :-) Is it just by Editing the source? — Preceding unsigned comment added by Koitus~nlwiki ( talk • contribs) 23:21, 24 February 2021 (UTC)
An electric field in a capacitor does NOT contain energy. The energy of a capacitor is in the electrons on the plates. In loading a capacitor a battery does work on the electrons (not on some field). The electric field is only the result of a created potential difference. So yes, a capacitor contains energy, but not its field but its electrons. Please, change the first sentence of this article. By the way, for a parallel-plate capacitor the E-field does NOT depend on z. Therefore, the equation is not consistent with the text. So change the equation too, please. — Preceding unsigned comment added by Koitus~nlwiki ( talk • contribs) 15:59, 24 February 2021 (UTC)
What type of capacitor do I need? I'm running a 120v generator that seems to have a voltage drop when the refrigerator comes on. This causes my stereo to shut off (automatic surge protection). I would like to end this problem. Thank you. 2001:5B0:4FDE:AE98:ADBD:2F77:5C4B:BAEF ( talk) 16:40, 4 February 2022 (UTC)