Talk:Ampere

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thread_title: [[User:LinkBot/suggestions/Ampere|Link suggestions]]

message: Now that I know that links are suggested automatically by a bot, I'll be less hesitant to remove ones that are fairly lame. 84.227.254.143 (talk) 06:18, 31 March 2014 (UTC)
thread_title: Linkbot suggestions

message: From what I can determine from the article, it seems that the ampere and the coulomb are defined in terms of each other. Am I correct in assuming this? Leenewton 3 July 2005 11:55 (UTC)
It appears that way at first, but if you read closer into the article you'll find the actual definition. (Something about two wires of infinite length and 1 newton of force between them.)
As far as the definition, is the sentence, "Although this is the internationally accepted definition, one should realize that it does not actually make sense, either grammatically or mathematically." actually meant seriously. It sounds like a joke (and a good one) so if it is true, it could maybe use some explanation. If it's a joke, I suggest we leave it.65.103.203.34 04:48, 7 February 2006 (UTC)
replies: text: The definition as it stands does not seem to actually define the direction of the current - the force will be in the same direction so long as the currents are parallel rather than anti-parallel, whether the currents are of positive or negative charges. Specifying the conductors to be metallic (electron currents) would seem to give the wrong sign for the direction of conventional (positive-charge) current flow. I can't see any way to fix the definition - it is inherently scalar unless one adds in the electrochemical cell definition of the volt with one terminal defined as positive and the other negative, for example.  —Preceding unsigned comment added by Enon (talk • contribs) 23:57, 17 May 2010 (UTC)

text: I added an introduction to the definition that explains the general idea of the definition. Is that better? --Jc3s5h (talk) 13:07, 12 March 2009 (UTC)

text: Any group of units could be declared base units so long as they will force all the other units to take on particlular definitions, and not create any contradictions. Which ones to choose would depend on being able to do experiments to realize the units with as little interaction among the definitons as possible, given the available technology. Jc3s5h (talk) 02:16, 15 January 2011 (UTC)
replies: text:  I might agree with 120 in that I think a more natural base unit is one of dimension electric charge and derive the unit of current from that and from the unit time.  But in fact, in the SI system, the ampere is defined first without a reference to time (except in the mechanical quantities).  The ampere is the amount of current flowing to get to a certain force per unit length.  The from that current and from the second, a unit charge is defined.  So it is the base unit from which other electrical units are derived.  But I would think it more natural to define base units in time, length, mass, and charge.  Although I know why the mole and candela are defined as base units, I really believe they are superfluous.  But I cannot deny their status as base units in SI. 71.169.180.190 (talk) 04:54, 15 January 2011 (UTC)
thread_title: Definition

message: I understand that C is used for specific heat so we couldn't use it for current. But is there a relationship between current and the letter "I"? Is it latin? thanks for help
: I've read *somewhere* that "I" was chosen since it stood for "Intensity". As a consequence, electrical engineers use "j" where mathematicians use "i" for the imaginary unit. With only 26 letters, overloading will occur, which is why advanced mathematicians must know English, Greek, Hebrew and other alphabets. ( Oh, and you can sign your posts with --~~~~, or use the signature button in the default editor.) --Wtshymanski 20:44, 29 September 2005 (UTC)
replies: text: Indeed, it's explained in the electric current article. --Mudd1 (talk) 01:07, 19 January 2014 (UTC)
thread_title: Why is the letter "I" used in the mathematical formula?

message: How does a layman judge amps as a unit of electricity? How can the term be understood by layman? Ill give you an example from an article about diesel-electric locomotives: This 270,000-pound (122,470-kg) locomotive is designed to tow passenger-train cars at speeds of up to 110 miles per hour (177 kph). The diesel engine makes 3,200 horsepower, and the generator can turn this into almost 4,700 amps of electrical current. The four drive motors use this electricity to generate over 64,000 pounds of thrust.
Now, what in the blazes does this term  4,700 amps of electrical current mean? I usually hear of the term "kilowatt". If a reader can't figure it out from the article, it's useless. (The same article goes on to measure another generator as producing kw.)Scott Adler 08:16, 6 August 2006 (UTC)
replies: text: if the reference to amps in that other article is uninformative, take it out.  but the definition here is, i think, physically explicit.  amperes is a measure of electric current, how rapidly electrical charge is moving past a boundary of some sort.  it is precisely a Coulomb per second, but the ampere is defined first (from this setup with parallel wires and magnetic force) and then the coulomb is defined to be the charge that passes, in 1 second, a boundary of which a 1 ampere is flowing. r b-j 02:54, 7 August 2006 (UTC)

text: Without specifying the voltage, the amperage figure is useless. --Urhixidur 14:13, 7 August 2006 (UTC)
replies: text:  the ampere figure is useful for telling one how fat the conductors have to be.  (the voltage would be useful to determine how much insulation they need on those conductors.) r b-j 17:39, 7 August 2006 (UTC)
thread_title: Ok, experts - but what is an Ampere?

message: The definition is inconsistent. At one point the article says at an ampere is the "amount" of charge, and later it says that an ampere has nothing to do with quantity. This is patently inconsistent. PLEASE CHANGE IMMEDIATELY. 76.24.28.237 00:23, 1 September 2007 (UTC)
replies: text: You need to distinguish between the definition and the relationship to charge.  The definition is not in terms of charge, but in terms of forces, lengths, and such already defined base units.  Charge is defined later as a derived unit.  This is not so intuitive, but is the way the SI system is built up.  An ampere is indeed an amount of charge displaced per second, but that's not how it is defined.  It's not inconsistent. AND WHAT'S THE RUSH? Dicklyon 00:31, 1 September 2007 (UTC)

text: I re-ordered the section to make it more clear.  I hope you find it less contradictory. Dicklyon 00:40, 1 September 2007 (UTC)
thread_title: Definition, Again

message: This spec sheet: http://www.thunder-sky.com/pdf/200725164258.pdf , talks about current in unit of CA.  What is CA?  Thanks, Daniel.Cardenas 14:46, 4 October 2007 (UTC)
replies: text: In the battery charging rate 3CA, the A is for Amps and the C is for capacity, made nondimensional.  If you have a 1 AmpHour battery, C is 1, and you can charge it at 3 A.  Usually the A is omitted and his is referred to as a 3C charge rate, meaning you can charge the battery in not much more than 1/3 hour. Dicklyon 18:38, 4 October 2007 (UTC)
replies: text: Yes that's what it means; no it doesn't belong in the Ampere article. Dicklyon 23:46, 4 October 2007 (UTC)
thread_title: What is CA?

message: What is the difference between a 5 amp plug and a 16 amp plug and
for which different electrical appliances these are used.  Vivek.  —Preceding unsigned comment added by 124.253.3.21 (talk) 06:23, 30 April 2008 (UTC)
replies: text: I have put a title on this section, based on the IP address 124.253.3.21 being in India. Perhaps someone familiar with electric power in India can answer. --Gerry Ashton (talk) 13:28, 30 April 2008 (UTC)
thread_title: Plugs in India

message: what is aparameter  —Preceding unsigned comment added by 196.0.25.118 (talk) 16:07, 27 May 2008 (UTC)
replies: text: The word "parameter" does not appear in the article, nor on this talk page; where did you see the word? One meaning is an argument to a mathematical function. --Gerry Ashton (talk) 16:12, 27 May 2008 (UTC)
thread_title: What is a parameter?

message: Enquiring minds want to know.  This page is the target for redirection from "Yottampere" yet there is no mention of what a Yottampere is on this page.  I'd add it myself but I don't know what it is.220.237.63.219 (talk) 06:21, 2 September 2008 (UTC)
thread_title: What is a Yottampere?

message: The dubious numbers in this article appear to come from a fake quote, one nowhere to be found in the cited source.  Gene Nygaard (talk) 17:34, 23 December 2008 (UTC)
replies: text: I've removed the dubious numbers, and revised the "Proposed future definition" section to be more in line with what's in the cited sources, so hopefully this issue is now fixed.  Djr32 (talk) 19:25, 8 March 2009 (UTC)
thread_title: Dubious

message: If I am giving 500 'A', what voltage should i maintain and how.
Please even show me the calculation on how should I keep the track of voltage according to the Amperes.
(122.167.235.238 (talk) 07:04, 4 March 2009 (UTC)
replies: text: What kind of load is the current flowing through? Is the current DC or AC? --Gerry Ashton (talk) 16:29, 4 March 2009 (UTC)
thread_title: ampere

message: The NIST standards for SI units requires that units be lower case unless the unit is based on a human name.  E.g. Hertz or Hz is correct.  hz is not.   See NIST section 6, 6.1.2   Both Amperes and Coulombs must be capitalized.128.95.172.173 (talk) 02:34, 29 October 2010 (UTC)
replies: text: The proceeding paragraph is complete nonsense. Jc3s5h (talk) 03:06, 29 October 2010 (UTC)
replies: text: Indeed.] Do these guys just not know whatever the hell they be talking about (yet insist on presenting themselves as expert) or are they deliberately trying to screw things up? 70.109.176.87 (talk) 03:45, 29 October 2010 (UTC)

text:  Don't stop the quote there. The very next sentence is: In keeping with this rule, the correct spelling of the name of the unit °C is “degree Celsius” (the unit “degree” begins with a lowercase “d” and the modifier “Celsius” begins with an uppercase “C” because it is the name of a person).188.192.109.185 (talk) 15:25, 6 December 2012 (UTC)
thread_title: capitalization

message: Interesting additions: Examples of how many amps various common appliances draw, what ratings are common on fuses and circuit breakers around the world, whether they are different for 120V or 240V countries, etc. -- Beland (talk) 02:46, 24 January 2011 (UTC)
replies: text: I have added a section "Everyday examples".  Does this section have the correct structure? If so, I will collect some references for the various statement made.  Also, should we restrict ourselves to everyday examples, or should we look at industrial systems? In either respect, the list should be kept short. Martinvl (talk) 14:10, 25 January 2011 (UTC)
replies: text: That structure is fine, though as we fill it out it would be helpful to have apples-to-apples comparisons for the U.S. vs. Europe. Thanks for your work on this!  -- Beland (talk) 18:40, 25 January 2011 (UTC)

text: Yes only life and light output change, but by large enough factors that the difference is significant. In the US, it is common to use 130V lamps in industrial environments where lamp changing cost is large enough to shift the optimum, compared to 120V for home use. I suspect in 220V countries, 240V lamps could be used the same way. You would not want to use 220V lamps at 240V for normal use. The efficiency of induction motors can be significantly different. Switching power supplies for electrical equipment can run over a wide voltage range. Gah4 (talk) 05:40, 27 April 2018 (UTC)
thread_title:  Examples 

message: Physicists definition would refer to charge penetrating a Gaussian surface per unit time, not passing a point.  Only in one-dimensional conductors would current be the charge rate passing a point.  I've added "passing a point in a circuit," although there might be a better resolution somewhere between a physicist's version and a non-scientific version. 128.95.172.173 (talk) 02:41, 1 June 2011 (UTC)
replies: text: How about something to the effect, "passing through a cross-section of a conductor"?  Such terminology informally describes a surface that (effectively) completely traverses the path of all the charge carriers, is compatible with the Gaussian surface concept, and neatly allows for the fact that nearly all charge carriers travel on the surface of conductors (see Hall Effect).  Also, (based on my experience as an EE) this kind of phrase is commonly used in texts that address basic electric theory. --69.255.17.51 (talk) 19:19, 5 June 2011 (UTC)
replies: text: I have reworded the lede, removing one of the occurences of the word "point".  The other occurence is qualified as being a "point of an electric circuit".  I am not convinced that all currents travel on the surface of conductors - what are the mechanics of current conduction in lightning or in plasmas.  (This is not a rhetorical questions - I do not know). Martinvl (talk) 20:28, 5 June 2011 (UTC)
thread_title:  Charge passing a point, per unit time 

message: Please discuss these changes at Wikipedia talk:WikiProject Measurement#Changes to the ledes of many SI-related articles.  Martinvl (talk) 18:26, 19 November 2011 (UTC)
thread_title:  Revocation of 19 November 2011 

message: I reverted recent changes made by User:Hgrosser on 3 October 2012.  The reasoning was:
*(S)He removed a number of "hard" spaces in the text.  It is usual to include a "hard" space ( ) when writing something like "3 A" as this ensures that there is no line break between the "3" and the "A".  This is in accordance with WP:MOSNUM and also international standards.
*I reinstated the the original values of current drawn by various domestic appliances.  I notice that Hgrosser appears to be American - I am British and I was writing about European appliances.  I took the values from appliances around my own home.  BTW, in the UK, an "Immersion heater" is an electical hot water supply.  The type of immersion heater shown in the picture in Wikipedia is illegal in the UK as it is regarded as a fire risk. Martinvl (talk) 06:06, 3 October 2012 (UTC)
replies: text: That would be original research then.  There is no European mains supply at 230 volts (see above).  What makes you think that the type of immersion heater illustrated is illegal in the UK?  I can buy one in almost any hardware or electrical supplier. In any case: so what?  It is an immersion heater and that is what that article is about.  86.159.159.194 (talk) 12:18, 7 November 2012 (UTC)
thread_title:  Revocations of 3 October 2012 

message: Hebert Peró (talk) 23:17, 11 March 2014 (UTC)
replies: text: This is tricky. Vacuum cleaners are commonly advertised in amps, but given the power factor for inductive loads, that isn't very useful. Gah4 (talk) 05:43, 27 April 2018 (UTC)
thread_title:  Popular Use of the Term Ampere 

message: What blithering crap. Leave physics to physicists. An amp is a couloumb per second. DOne,  — Preceding unsigned comment added by 165.201.140.130 (talk) 20:13, 13 May 2014 (UTC)
thread_title:  Ouch 

message: All batteries I know of are rated in Amp-hours (big ones) or mA H (small ones), not in C or mC. The article suggests that they are in C. Gah4 (talk) 14:20, 25 October 2015 (UTC)
thread_title:  Batteries 

message: The definition really should point out that (a) the current definition also fixes the value of the permeability of free space, and (b) in effect, the current definition in effect defines the Amp by defining the permeability of free space as a fixed value (the theoretical experiment involving parallel wires really just being a rather convoluted way of getting permeability involved)  — Preceding unsigned comment added by 94.196.243.2 (talk) 11:45, 13 March 2016 (UTC)
thread_title:  Definition section 

message: I had thought that the US NEC limited the current for usual (type A) plugs from 15A outlets to 12A. I was going to change the values, but it seems that there are 1800W (15A) toasters. I believe it is 12A for hair dryers, though. You can watch them get closer, and finally reaching 1440W.  I don't have a current NEC to look it up. Gah4 (talk) 08:48, 1 April 2016 (UTC)
thread_title:  NEC and typical currents 

message: How should we fix it?
:Actually it's hard to say which is worse, the fact that the new definition makes the page out of date, or the wording of the new definition itself, which contains undefined terms like A and ∆ν.  (The latter refers to the unperturbed ground-state hyperfine transition frequency of the caesium-133 atom, namely 9192631770 Hz, but a casual reader of this Wikipedia article might not immediately recognize it as such.)  In my case I came to this article because I needed the exact definition of the ampere, which I had to go elsewhere to find since this clearly was not it.
:Since elementary charge (that of a proton) is so fundamental, I don't understand why the coulomb was not defined as a certain number of elementary charges and an ampere as one coulomb per second.  All I can think is that the electronvolt should be a certain number of joules, namely 1.602176634\times10^{-19} joules exactly, and that this relationship for some reason takes precedence over the number of electrons in a coulomb.  Had the latter been used it would have been natural to make it an integer, as with the Avogadro number.  In fact the reciprocal, 6241509074460762607.77624098... is not quite an integer, falling short by about 9/40 of an electron, .223759... to be more precise.  Vaughan Pratt (talk) 19:21, 11 July 2019 (UTC)
replies: text: The new definitions are all in 2019_redefinition_of_the_SI_base_units.  It doesn't explain the reasoning behind the definition of the charge of the electron, though. Some are to make the uncertainties come out small enough, and in the right places.  I was wondering not so long ago, why Avogadro's number was not a multiple of 12, such that an integer number of C-12 atoms would be in a gram.  Again, I didn't try to follow the math. Since coul/electron is used in calculations more often that electrons/coul, maybe that is the reason. Gah4 (talk) 21:37, 11 July 2019 (UTC)
thread_title:  This page is very out of date because of the redefinition 

message: To improve consistency, shouldn't the title be "Ampere (unit)"?  — Preceding unsigned comment added by Davidhaugs (talk • contribs) 13:01, 6 February 2021 (UTC)
thread_title:  Change the title to "Ampere (unit)"? 

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thread_title:  A Commons file used on this page or its Wikidata item has been nominated for deletion