Talk:Capacitor

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e·h·w·Stock post message.svg To-do:
  • Expand the History section: what about more modern developments (Surface mount components etc)? Needs a lot of references!
  • Add references to theory section and copyedit
  • Draw a diagram of the equivalent circuit and add to the appropriate section
  • Improve references in nonideal behaviour section
  • Copyedit and improve references in Capacitor types section
  • Restructure and tidy the applications section: there are too many small sections!
  • Add references to the safety section

Units[edit]

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)

Here's a capacitor marked as 22 nF: http://www.ciel-electronique.com/catalogue/Larges/CA122NF500V.jpg
Here's one marked as 4.7 mF: http://img109.imageshack.us/img109/9711/3r8n.jpg
Not that this matters much, because on most capacitors (as with many other electronic components) the value is written in shorthand that doesn't explicitly state the prefix. It's not a very good idea to base Wikipedia style policies on component markings. After all, you wouldn't expect people to write resistances as colour codes, would you?
What confusion exactly is mF subject to? It unambiguously means millifarad. If you're talking about the obsolete "mfd" abbreviation, I don't believe that is a relevant issue anymore; any significance "mfd" has is of a purely historical nature. But if you really believe there is still the possibility for confusion (even though, as I noted on my talk page, at least one instance of mF has been in the article for over a year, possibly a lot longer, without anyone raising concerns over it), how about changing the first occurrence of mF to millifarads (mF) ? Would you find that satisfactory?
Indrek (talk) 22:01, 18 July 2014 (UTC)
@Indrek: 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. Piguy101 (talk) 23:16, 18 July 2014 (UTC)
I believe that nanofarads is acceptable, but millifarads should not be in the article. This is simply because it is not standard usage (I have no idea why, though). I suppose that changing the first occurrence of mF to millifarads would work. Piguy101 (talk) 23:23, 18 July 2014 (UTC)
Although this may be a bit WP:CIRCULAR, the article on Farad says "The millifarad is not used in practice; a capacitance of 4.7 mF (0.0047 F), for example, is instead written as 4700 µF." Piguy101 (talk) 23:26, 18 July 2014 (UTC)
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)
You're right about the sizes; voltage affects size as much as capacitance. Unfortunately, I cannot see the voltage rating of the blue capacitor in the photo, so I guess that my statement is null. Here is my proposal: nonafarads is fine and the first mention of mF should parenthetically say millifarads. Can we do this? Piguy101 (talk) 12:28, 19 July 2014 (UTC)
Adding to myself: the 10000 uF capacitor in the photo should be labeled as both 10000 uF and 10 mF. Piguy101 (talk) 12:33, 19 July 2014 (UTC)
Both of your suggestions sound good to me. Waiting for @AlanM1's opinion. Indrek (talk) 15:20, 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):

  • Gates, Earl D. (2012). Introduction to electronics (6th ed. ed.). Clifton Park, NY: Delmar Cengage Learning. p. 128. ISBN 9781111128531. 
  • Adlington], [editors, Chris Humphries, Steve Luck, Frances (1999). Philip's illustrated encyclopedia. London: George Philip. p. 301. ISBN 9780540077182. 
  • Dummer, S.W. Amos, R.S. Amos ; appendix by G.W.A. (2002). Newnes dictionary of electronics (4th ed., pbk. ed. ed.). Oxford: Newnes. p. 43. ISBN 9780080524054. 
  • Raghuveer, K.A. Krishnamurthy, M.R. (2001). Electrical, electronics and computer engineering for scientists and engineers (2nd ed. ed.). New Delhi: New Age International (P.) Ltd., Publishers. p. 82. ISBN 9788122413397. 
  • Carr, Joseph J. (2002). RF components and circuits (1st ed. ed.). Oxford: Newnes. p. 209. ISBN 9780080498072. 
  • Durgapal, R.S. Gambhir, D. Banerjee, M.C. (1995). Foundations of physics. New Delhi: Wiley Eastern. p. 22. ISBN 9788122405231. 
  • --, prepared by the Bureau of Naval Personnel. (1970). Basic electricity (Second revised and enlarged edition. ed.). p. 191. ISBN 9780486172668. 
  • Gregersen, edited by Erik (2011). The Britannica guide to electricity and magnetism (1st ed. ed.). New York, NY: Britannica Educational Pub. in association with Rosen Educational Services. p. 183. ISBN 9781615303052. 
  • Jr, Louis E. Frenzel, (1988). Crash course in electronics technology (1st ed. ed.). Indianapolis, Ind., U.S.A.: H.W. Sams. p. 95. ISBN 9780672224942. 
  • Herman, Stephen L. (2011). Alternating current fundamentals (8th ed. ed.). Clifton Park, NY: Delmar Cengage Learning. p. 102. ISBN 9781111125271. 
  • Gupta, S. S. (2007). Electrical Engineering (O.T.). Firewall Media. p. 159. ISBN 9788170080886. 

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)

If you want to see technical literature that uses nano- and millifarads, just search Google Books, there are plenty of results. Nanofarad seems to be much more common than millifarad, probably (as I mentioned above) because capacitors in that range are more common than caps in the millifarad range. Sorry, but your argument doesn't make any sense to me. I could probably find a dozen electronics books that don't mention the gigaohm, but does that mean we should avoid that unit? No. It's a standard SI unit and prefix, just like nanofarad and millifarad, to be used for denoting component values when the value is in an appropriate range.
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.
By the way, let me ask you this. Suppose the article had a picture of a capacitor marked in millifarads (such as the 4.7 mF one I linked to above). Would you caption that as "4.7 mF" or "4700 μF", and why? Indrek (talk) 10:52, 20 July 2014 (UTC)
To answer the last question, we should caption the capacitor with the labeling on the picture, regardless of the prefix. This will be the least confusing for the readers. The reason why I am not totally for using millifarads is the historical confusion of mF and uF. Since the largest capacitors almost exclusively dominated the uF range, there was no confusion between using mF as the same as uF. Part of this may be the result of not wanting to type 'mu' when m could be typed instead. Although this is just a forum, it contains several reasons why mF is not in popular usage: Millifarad VS Microfarad abbreviation Piguy101 (talk) 15:10, 20 July 2014 (UTC)
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. Looking at the books hits for nanofarad, I'll first note that there are about 1/40th as many hits as microfarad.
"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. Convention is what it is, and doesn't always have to be consistent or even explainable, though it's nice when it is. The gigohm seems to be a work-in-progress, largely related to biomedical work and theory.
In the case of the 10,000 μF cap, it's a nit-picky thing, but we don't know the precision of the value, given no other information. If it's 5 sigfigs, we'd have to convert it to 10.000 mF, which is just ugly. If it's 0 or 1 sigfigs, 10 mF is correct. How about the tolerance, and how does the range of values there compare with the precision issue? Or maybe we should just stick to the value as marked and not risk implying anything other than we can see.
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".
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.
I would caption a 4.7 mF cap as "4.7 mF" first, possibly followed by "(4700 μF)" if it were in a section where the value was of particular importance, like size comparison. —[AlanM1(talk)]— 19:33, 20 July 2014 (UTC)
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 is Yes, 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.
Also, "looks weird" is very subjective. For instance, to me "10000 μF" looks weird, as does "0.047 μF".
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.
So instead of speculating about the prevalence or rarity of the milli- and nanofarad, we should ask - what is the actual problem with using them on Wikipedia? Not in electronics books, or spec sheets, or on actual capacitors, but here on this website. You've mentioned possible confusion with "mF", but apparently that hasn't been a problem for anyone else over the year or more (possibly a lot more) that it's been used in this article (and probably numerous other articles). Have you considered that maybe it isn't really an issue after all? Indrek (talk) 07:33, 21 July 2014 (UTC)
I started to respond point by point, but I don't see getting past what appears to be an WP:ENGVAR-type problem. 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. This justifies not using nF (or at least not going out of our way to do so). I really don't see any support for using mF. I am surprised that the conversation has attracted so little attention, and would welcome a wider audience. Perhaps an RfC? —[AlanM1(talk)]— 08:37, 22 July 2014 (UTC)
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)

But we're not in the capacitor industry here, this is a digital encyclopaedia, and we're not necessarily burdened by the same constraints and considerations. What "misunderstandings" exactly do you think "mF" is subject to that apply to Wikipedia? And why wouldn't any of the standard approaches for dealing with potentially unfamiliar or ambiguous terms in Wikipedia articles (e.g. providing an explanation in parentheses, or linking to another relevant article, as have been suggested above) not work in this case? Indrek (talk) 12:54, 22 July 2014 (UTC)
Just to expand on my previous comment. On Wikipedia, when an article contains a word or term that's potentially unfamiliar, ambiguous or confusing to readers, the best solution isn't necessarily to remove it. There are often better options. For instance, when a computing-related article uses the petabyte (a unit so large many readers might not have come across it), it might do any or all of the following:
  • fully write out the unit, e.g. "40 petabytes (PB)"
  • duplicate the value in another, more easily understood unit, e.g. "1 PB (215 bytes)"
  • make the first occurrence of "PB" a wikilink to the Petabyte article
Any of those would also be a suitable option for nanofarads and millifarads (assuming these claims of confusion and misunderstandings can be substantiated).
Also, there's some interesting reading on the subject here: Why do Americans not use nanofarads? Notably, a number of Americans there are saying they have no problem with using the nanofarad. Obviously it's largely anecdotal evidence, and I'm not trying to build an argument here, just adding this to complement the link Piguy101 posted above to the same forum. Indrek (talk) 20:08, 22 July 2014 (UTC)
The problem I see is that mF and MFD are still found in many diagrams and even on many caps as the symbol for microfarads. (See the first photo in the Applications section for just one example.) That's where it often gets confusing. I don't really think it's our place to promote the usage of uncommon terms, valid as they may be, or to try to influence industry standards. (Why not the myriadth-farad too? By that reasoning, we should go around and change every unit of centimeters larger than 10 into decimeters.) I also don't think it is necessary to strive for the shortest number possible, because we're not running short on print space here. Zaereth (talk) 22:31, 22 July 2014 (UTC)
For reference, I took the liberty of changing the text of the photo to match it. I believe that the current prefixes of the article are clear and unambiguous. Piguy101 (talk) 16:58, 23 July 2014 (UTC)
FWIW, I too am content with the prefixes used in the article (as of this revision). Indrek (talk) 17:50, 23 July 2014 (UTC)

Overall opinions[edit]

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 believes that nF and mF should be avoided because they are not commonly used. I concede that nF may be used in Europe, but we should not go out of our way to use a unit that is only common in some places when μF and pF are familiar to all.
I want to point out to everyone in this discussion that words like 'nano' or 'pico' are not units but [[1]]. They are scale factors for units and have absolutely nothing to do with the units themselfs. The unit in question is F, Farrad, not microfarad, not picofarad. The prefixes are the same ones as used for all other existing units. Understanding these prefixes is a general thing and not specific to Farrads. Anyone working with SI units should understand these because otherwise any unit with prefixes will be confusing. If you get confused by the use of n(ano) instead of p(ico) then you were confused before that and it simply means you do not understand scientific unit scaling. This is pretty elementary stuff.83.87.238.229 (talk) 16:09, 30 August 2014 (UTC)
  • Indrek believes that because nano and milli are standard SI units and there's no evidence of them actually being confused or misunderstood on Wikipedia, they should be used to make the numbers more readable.
Again, prefixes are not units. 83.87.238.229 (talk) 16:09, 30 August 2014 (UTC)
  • Piguy101 believes that nF is acceptable, but mF should be generally avoided. He believes that the current state of the article is acceptable.
  • Elcap believes that mF should be avoided because of the confusion with μF.
According to their definition there is no confusion. The character 'm' never denotes 'micro'. If it does someone is doing something wrong. 83.87.238.229 (talk)
  • My general opinion is that we should stick with standard usage, so as not to confuse any readers. It is not uncommon in units of measurement to skip entire orders of magnitude, just to avoid the added math. In linear measurements, for example, they usually go from centimeter straight to meter. Rarely ever do you find measurements listed in decimeter. Although it is a valid measurement, it is just not commonly used. Perhaps it would be helpful to explain in the article that some orders of magnitude are not in common usage and why. The book Domestic Engineering (1918) says, "This remark was read with interest for there is a great need to eliminate a number of synonymous symbols and arrive at an international standard. ... The symbol for the millifarad is given and used throughout for the microfarad." The book Encyclopedia of Electronic Components Volume 1 says that the nanofarad is common in Europe, but rarely in the US. Zaereth (talk) 19:37, 22 July 2014 (UTC)
You refer to a book from 1918. That's a pretty bizarre notion as there is no comparison between our world of standards and 1918's world of standards. I don't know if you've noticed, but things have changed a bit... 83.87.238.229 (talk) 16:09, 30 August 2014 (UTC)
  • I feel nF is marginally acceptable but that mF should be avoided; in a general reference encyclopedia we should use the most universally accepted units. I'd like to see usage of mF removed from the article. --ChetvornoTALK 23:14, 31 July 2014 (UTC)

Closure and consensus[edit]

@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)

No objections here. Let's give it a couple of days and if no one else objects, I guess we can consider consensus to have been reached. Indrek (talk) 19:35, 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:

  • U: Use as needed to produce a value in the 1–1000 range;
  • M: Mention to describe why it is less common, use only in captions when the object pictured is so labeled; or
  • A: Avoid use, other than to describe why it is less common.
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 here From 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.
As for the centi-, deci-, deca- and hecto- prefixes, I don't think Piguy101 meant to suggest those should also be used. As I've mentioned already, they are currently explicitly discouraged by the MOS, and no one here has expressed desire to change that. Indrek (talk) 05:49, 1 August 2014 (UTC)
Other than giving my $0.02, I wasn't really trying to get involved in a discussion. The reason being that my time is very limited right now, so it is not easy to keep up. In my general opinion, I would probably add "A" to both of those categories, since I feel it is best to avoid them, except to explain that they are uncommon. I feel less strongly about nF than mF because mF can get confused with uF, as I mentioned above. Perhaps nF should simply be left to WP:ENGVAR to decide? Zaereth (talk) 00:19, 1 August 2014 (UTC)
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)
@Indrek: Although this source is a blog, it shows the confusion between mF and μF: Is mF and mFd the same as uF? Will the real Microfarad please stand up? And the author says that they are all identical units, although he is not ignorant and does note the difference between millifarad and microfarad. We should not worry uF and μF problems, as long as we use the correct "mu" in the article. As said earlier, I am not opposed to mF as long as (10-3 F) follows it for the first instance. How's this? Piguy101 (talk) 12:13, 1 August 2014 (UTC)
Thanks for the link. I see it primarily discusses "MFD", which is another non-standard abbreviation that Wikipedia doesn't use. All that link says about "mF" being misused for denoting microfarads is "Some older capacitor manufacturers" and "some other sites". Hardly evidence of any real confusion, and definitely not relevant for us in the context of a digital encyclopaedia. As you say, so long as we use the correct symbols, we shouldn't have anything to worry about.
As for your suggestion, I'm fine with it; it's precisely the sort of approach I've advocated myself - explaining/disambiguating the unit instead of avoiding it. Indrek (talk) 13:28, 1 August 2014 (UTC)
It just seems common sense to me. Why use terms the reader will never find in real life. People are actually going to try to use the information we provide them, and when we say that a cap marked 10 M, or 10mF, stands for millifarads when it really stands for microfarads, I foresee some ruined projects and some very unhappy readers.
For a source, the book Hands-On Electronics: A Practical Introduction to Analog and Digital Circuits by Daniel M. Kaplan, Christopher G. White, says on page 19: "For some reason the various manufacturers' conventions for marking capacitors are particularly confusing --probably it has to do with the fact that many small-value capacitors are physically too small to permit much printing on them. Some common sense is required. Keep in mind that 1 Farad is a huge unit! Most capacitors are in the picofarad and microfarad range. A physically large capacitor that says '10M' on it is usually 10 microfarads, not millifarads (for some reason, most manufacturers don't want to print Greek letters, so they use 'M' instead of 'u.' A 10 millifarad capacitor would be labeled '10000M. A capacitor that just says 10 on it is 10 picofarads." Zaereth (talk) 18:53, 1 August 2014 (UTC)
Crystal Clear action edit add.png Added a mention of that to the article: [2] Piguy101 (talk) 20:22, 1 August 2014 (UTC)
I would like to note that there is only one use of millifarad in the entire article. It is in the lead and is followed with (10−3 F), so it is unlikely ambiguous. This debate, mostly regarding the merit of the millifarad, is therefore quite silly. Piguy101 (talk) 19:23, 1 August 2014 (UTC)
I agree. I was asked for a source, so I provided one. Other than giving my two cents, I'm not really too invested in this discussion, so I'll leave it to you all to work out. Zaereth (talk) 19:31, 1 August 2014 (UTC)
@Piguy101: 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.
@Zaereth: 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.
So what would qualify as "evidence", you might ask? Previous talk page discussions about this subject, for instance. Edit requests from confused readers. Actual edits in articles' histories, perhaps going back and forth between the two formats, showing this to be a controversial issue. Basically anything that shows a significant number of people have a problem with "mF" and/or "nF" being used on Wikipedia. Because right now the notion of avoiding those abbreviations is seeming more and more like a solution looking for a problem. And not a very good solution, either. Indrek (talk) 20:34, 1 August 2014 (UTC)
By evidence, I assume you mean original research? I will provide none. I only deal in sources when working on an encyclopedia, and that was merely the first one that popped up. And please, there is no need to repeat to me what I said. I am aware of what I wrote. Like I said, I have very little interest in this debate, and very little time to pursue it, so don't be surprised if I do not respond further. Zaereth (talk) 21:31, 1 August 2014 (UTC)
By "evidence", I mean evidence. Something to substantiate these claims of confusion and misunderstanding that are being made, and to show that they're relevant to Wikipedia.
Your stance on sources, while admirable, is misguided in this particular case because we're not debating article content here. WP:OR doesn't apply to guidelines like the MOS (which is what governs unit and prefix usage, among other things) because they're not based on what external sources say, but on what the Wikipedia community agrees upon.
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)

Fine with me, although it seems there may be some confusion with regards to what exactly this debate applies to (writing style, not article content), so whoever posts the RfC should make sure to clarify that. Indrek (talk) 06:42, 2 August 2014 (UTC)
Why on earth should the notation in this article be dictated by the vagaries of manufacturers' codes? Perhaps we should also go through the resistor article and change phrases like "a 56 kΩ resistor" to "a resistor", so as not to confuse poor readers who might be unfamiliar with space-age hieroglyphics like "kΩ". Zueignung (talk) 16:23, 3 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. --ChetvornoTALK 22:17, 25 September 2014 (UTC)

History[edit]

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 deserves a mention in History[edit]

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)

Benjamin Franklin deserves a mention in History[edit]

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

Not disagreeing, but this article is about the electrical component. Not every odd shape that can hold a charge is needs to be included. Constant314 (talk) 06:04, 1 December 2015 (UTC)

Parallel vs. series network: voltage and current output when discharging[edit]

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)

Capacitors in series, for all intents and purposes, increase the total thickness of the dielectric, so they can be used at higher voltages. (It's a little more complicated than that, but...) Just like two 1.5 volt, AA batteries in series become 3 volts, two 450 volt capacitors in series will be able to handle 900 volts. The drawback is that it cuts the capacitance in half and increases both inductance and resistance.
In parallel you get more capacitance (thus more amps), but at no more than the designed voltage.Zaereth (talk) 01:33, 6 August 2016 (UTC)
On a side note, I notice this article doesn't mention the use of capacitors to actually increase system voltage (a phenomenon usually relegated to power supplies), such as voltage multipliers. I'll look up some sources and maybe add enough to provide a link to the article. Zaereth (talk) 22:03, 11 August 2016 (UTC)