# Talk:Electric charge

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## To do:

Charge and Noether's theorem, gauge theories.

Please repair the History section due to vandalization (I'm not familiar enough with Wiki to do this myself right now). —Preceding unsigned comment added by 74.11.107.246 (talk) 00:03, 10 March 2009 (UTC)

There is an inconsistency beetween the introduction who say "Electric charge comes in two types, called positive and negative" and "There is only one kind of electrical charge, and only one variable is required to keep track of the amount of charge" which come later(in Electrification by friction). —Preceding unsigned comment added by 129.241.164.154 (talk) 12:22, 4 February 2011 (UTC)

I'm not sure if this has been actioned but the introduction still says there are two types of electric charge. Surely there is only one type of charge and a anti-charge, charge is from the U(1) part of the Standard Model so don't see how it can have two.Dja1979 (talk) 01:25, 4 November 2012 (UTC)
It is just an attempt to use very simple language, because people reading the article might have no idea what charge or electricity is. If you can think of a better wording, feel free to change it. :-)
I don't suggest using the word "anti-charge" in the second sentence ... I think it would sound like nonsense to a non-physicist. But I'm sure you can think of other wording too. :-) --Steve (talk) 13:12, 4 November 2012 (UTC)
I think the sentence There exist two types of electric charges, called positive and negative. could be replaced by An object can be either positively or negatively charged. or Charge can be either positive or negative.. Ulflund (talk) 13:25, 4 November 2012 (UTC)
Personally I like Charge can be either positive or negative. As an object can neutral as well as positively or negatively charged.Dja1979 (talk) 13:38, 4 November 2012 (UTC)

## removed

I removed this also, since amperes are based on coulombs, not the other way around: - Omegatron

One coulomb (6.24 x 1018 charge carriers) can be defined as the quantity of charge that has passed through the cross-section of a Conductor (material)|conductor carrying one ampere within one second.

Actually no. Last time I checked, the Ampere is considered the fundamental unit, the A in MKSA, with the coulomb being an Ampere-second. -- Decumanus | Talk 22:38, 30 Mar 2004 (UTC)
Hmm... But the coulomb is a specific number of elementary charges, which are certainly a fundamental unit... I guess this needs to be explained, regardless. - Omegatron
You're right. sorry. - Omegatron
No prob. It's certainly counterintuitive in some sense. -- Decumanus | Talk 22:52, 30 Mar 2004 (UTC)
Confusion: the NIST uses the word "fundamental" in an odd way. Certainly the Coulomb is the more fundamental concept, since an Ampere is a *flow* of a certain number of Coulombs per second (you can't have coulombs-per-second without coulombs!) But in NIST terms, "fundamental" refers to a primary, directly-measured calibration standard, versus "derived" standards which are not measured directly. At one time the Coulomb was the "fundamental" standard. IIRC, the Coulomb was measured as a deposition of a certain amount of silver in an electrochemical cell. But Amperes are far easier to measure accurately by measuring the magnetic force between adjacent parallel conductors. So today, the electric current is the "fundamental" standard, and the standard for charge is then derived from the high-precision standard Ampere, rather than being measured directly. - --Wjbeaty 06:28, Feb 17, 2005 (UTC)

## Removed for confusion

"Before that experiment, charge was ordered in anion at cation, a term introduced by Michael Faraday."

## Conservation of Charge and Gauge invariance

Since the action (what action? perhaps this should be a link to a rare definition of 'action'?) is invariant under gauge transformations (due to the masslessness of the photon), by Noether's theorem the (something) is a conserved quantity associated with it (with what?). Since the langrangian density is

$\mathcal{L} = - \frac{1}{4} \mathcal{F}^{ij} \mathcal{F}_{ij} + A_i J^i$

plus other terms that do not involve the electromagnetic interaction, (something). since the contribution to the action by the first term is trivially gauge invariant, we need consider only the second. Under a gauge transformation Ai->Ai+∂iφ the action is increased by

$\int d^4x J^\mu \partial_\nu \phi = - \int d^4x \phi \partial_\mu J^\mu$

the only way for this to be satisfied for arbitary φ is if ∂μJμ=0, which is the continuity equation

## Homework question

anon comment:

Please can someone quickly and briefly explain how you create similar charges for two objects to repel (physically/practically rather than theoretically) Thank you in anticipation, a GCSE student

Try looking at the 'experiments with an electroscope' paragraphs on the Electrometer page.

--Light current 23:23, 9 February 2006 (UTC)

## What kind of variable is Q

"Q is a measurement of the charge held by an object."

Q isn't a constant or a unit, and isn't used in an equation on this page. Is this equivalent to saying "l is a measurement of the length of an object"? - Omegatron 00:23, May 31, 2005 (UTC)

## Quantized??

What does quantized mean? I keep running into and stumbling over this word!

It means something that isn't continuous in nature but rather, comes in small, discrete packets (quanta). For example, electric charge travels in the form of electrons, protons, etc. and they are individual units; you can't have "half the charge of an electron" or "an eighth of the charge of an electron"; it's either the whole charge or nothing. Such things that come in discrete little bundles are said to be quantized (as in quantities). At the super-ultra-microscopic level, most things are quantized and not continuous. It's only in our macroscopic world that they seem to be continuous because the quanta are so small.
See Quantum mechanics for much, much more.
By the way, you can "sign" your talk postings by including four tildes (~~~~) at the end of your posting. When you press "Save page", the tildes will be converted into your username (or IP address) in a handy Wikilinked format. A timestamp of your edit will also be included.
Atlant 18:12, 14 February 2006 (UTC)
But quarks have 1/3 and 2/3 of the charge of an electron. Maybe something should be mentioned about this.
GoldenBoar 18:11, 6 May 2006 (UTC)
It already is. Have another look at the article. --Heron 21:21, 6 May 2006 (UTC)

## more details about the experiment

"This property has been experimentally verified by showing that the charge of one helium nucleus (two protons and two neutrons bound together in a nucleus and moving around at incredible speeds) is the same as two deuterium nuclei (one proton and one neutron bound together, but moving much more slowly than they would if they were in a helium nucleus)."

Which experiment was this? How is it done? - Omegatron 00:26, May 31, 2005 (UTC)

## different kinds of discharge

See Talk:Spark_gap#Clarify the difference for some questions I have about the different kinds of discharge. - Omegatron 18:12, Jun 4, 2005 (UTC)

## electric charge density

Could someone explain " electric charge density"? Thanks. JDR

It's the quantity of electric charge per unit volume. Units: C/m3. --Heron 14:19, 25 September 2005 (UTC)

## Laymen Question

This is a very basic laymen's question. When discussing an electric charge, such as current that travels from a battery to say a light bulb, I have read in general that there is a flow of electrons. Electrons from where? For instance in chemical reactions one can determine from the reaction where the electrons traveled to and from.

Within a given current, where are these electrons coming from?

Thanks, BT

1. Yes, in metals there is a flow of electrons. Keep in mind that in other materials different charged objects can flow, like ions in salt water.
2. The electrons aren't coming from anywhere. They're already there in the metal. The current source is just pushing them in one direction. Think of wires as pipes already filled with water, and you are connecting a pump in a loop of such pipe, pushing the water in a circle. Does that help? — Omegatron 18:23, 9 October 2005 (UTC)

## Free and bound charges

Could free and bound charges be added to this article? I'd do it, if I could find better references than I have online. -- Kjkolb 12:15, 26 November 2005 (UTC)

I agree. I'm specifically interested in the "free electric charge density" refered to in gauss's law. Does "free" mean that it doesn't have a corresponding positive charge to neutralize it? It would be very good if this article had a section on both electric charge density and free electric charge - also noting the variable ρ ( rho - free electric charge density) and what it means. Fresheneesz 22:46, 9 February 2006 (UTC)
wow. Looking online for free electric charge density returns links to every freaking copy of the same definition of gauss's law... Everyone a plagiarist... Fresheneesz 22:52, 9 February 2006 (UTC)
Hi guys, I added a sentence about these. For more details follow the links to "Polarization density". Yevgeny Kats 23:06, 9 February 2006 (UTC)

## simple definition?

I think it would be nice if at the top of the page, before you got into all of the confusing terms, you had a simpler definition, or at least an example. Because this article is so well written that it is useless to people like me who have no idea what a subatomic particle, ore anything else on the page, is.

Does the history section not answer yor questions in simple language?--Light current 21:58, 19 March 2006 (UTC)

## My Suggestion for an article

For [1], I suggest that adding some brief deriviation on it.

For instance:

$\mathcal\, I_{output}=-\frac{dQ_{in}}{dt} \,$
$\mathcal\, \vec{J} \cdot \vec{dS}=-\frac{dQ}{dt} \,$
$\mathcal\, \vec{J} \cdot \vec{dS}=-\frac{ \partial{\rho}}{\partial{t}} {d \tau} \,$
$\mathcal\, \int_{s} \vec{J} \cdot \vec{dS}=\int_{\tau} -\frac{ \partial{\rho}}{\partial{t}} {d \tau} \,$
$\mathcal\, \int\int\int \nabla \cdot \vec{J} \, d\tau \, =\int\int\int -\frac{ \partial{\rho}}{\partial{t}} {d \tau} \,$
$\mathcal\, \nabla \cdot \vec{J} + \frac{ \partial{\rho}}{\partial{t}} =0 \,$

## Charge migration

The section about two types of charge is a little confusing. There is no positive flow per se, it is simply the illusion created by the counter flow of electron vacancies. This section seems somewhat unwieldy User A1 04:35, 9 January 2007 (UTC)

## James bond and the symbol q

Hello,

I have reverted the assertion that the symbol Q is related to the character from James bond, a quick search of some journals turns up articles using the symbols that clearly predate the fictional character I will assume at this point that you have simply made this assertion in error, but any further additions along this line may involve further action against your user. Thankyou User A1 05:23, 1 February 2007 (UTC)

## Removal of NPOV tag

Hello,

I removed the NPOV tag, as i did not believe that there is any reason for it. If anyone can tell me what the reason was for adding it, please comment. Thanks User A1 04:52, 22 February 2007 (UTC)

## Expansion.

Of itself this article is satisfactory, it is only when one reads other articles about the manifestations of electric charge, e.g. displacement current, that one sees the need for a more powerful illumination. I suggest expansion along the following lines.

Charge is a property of fundamental particles only; there are charge-like manifestations e.g. electron holes and ions; they only approximate fundamental charged particles, they are composites.

The term particle is too restrictive. A charged particle comprises its mass and its charge, it is characterised by an electric field that is infinite in extent. If this is appreciated the wave/particle dual nature of an electron is more easily understood; it is easier to understand why electrons passing through adjacent slits interfere with each other, even more so when one remembers that the moving charge generates a magnetic field.

The total charge of a particle is determined by integrating the electric field over any surface that encloses it only, however big. Looked at this way one may consider an electron as being infinitely big! It becomes much clearer why displacement current is the effect produced by a moving charge. May I say that, if the surface integration is changed so that a charge is included that was previously excluded, that charge flow has taken place, and that the corresponding current flow could be vanishingly small?Excitation 20:25, 24 February 2007 (UTC)

## several types of electricity

I deleted the line "Matter is actually composed of several kinds of electricity", since it really doesn't make sense. There's only one type of electricity, Coulomb charge. The line went on to mention different types of charged particles, which is correct, but it is misleading to suggest that there are many "kinds" of electricity. (especially when it is only two paragraphs later than the line stating that Faraday discovered that there was only one kind of electricity.) Geoffrey.landis 13:16, 28 June 2007 (UTC)

## Net charge of the universe

What is it? Anyone know? —Preceding unsigned comment added by 88.109.100.75 (talk) 02:22, 10 September 2007 (UTC)

## lowercase

Can we clarify the distinction in meaning between Q and q? — Omegatron 02:37, 3 November 2007 (UTC)

## Template:Electromagnetism_vs_Template:Electromagnetism2

I think the Electromagnetism template is too long. I created the alternative version shown in this article; see a more extended explanation at Talk:Electrostatics#Template:Electromagnetism_vs_Template:Electromagnetism2. Comments welcome!--DJIndica 17:21, 5 November 2007 (UTC)

## Hello?!

it doesnt say what is an electrically charged particle is

somebody please make a page abut it —Preceding unsigned comment added by 68.114.163.103 (talk) 02:18, 27 February 2009 (UTC)

## History

History section needs resourcing... Could somebody check the previous edits and make the changes ? I tried undoing uptil the last best version but couldn't... Thanks WikifingHelper (talk) 19:09, 16 March 2009 (UTC)

I restored the History section from this version: [2]. --Kkmurray (talk) 00:50, 17 March 2009 (UTC)

## Overview

I think there is a problem with the following statement: "This charge is often zero, because matter is made of atoms, and atoms all have equal numbers of protons and electrons. More generally, in every molecule, the number of anions (negatively charged atoms) equals the number of cations (positively charged atoms)." If all atoms have equal numbers of protons and electrons, then how do we explain anions and cations?? And there are plenty of molecules that have a non-zero charge. for example, most proteins are charged.Pedunculopontine (talk) 19:57, 22 July 2010 (UTC)

## units

charge has units of M^(1/2)*L^(3/2)*T^(-1)

M = mass
L = length
T = time

Just granpa (talk) 06:30, 5 March 2012 (UTC)

This is true in Gaussian units, false in SI units. What's your point? --Steve (talk) 13:38, 5 March 2012 (UTC)

## The section "Properties"

I think the section "Properties" there is either an error or vandalism. I think, the faster the electricity flows, the more energy you get. The voltage (difference in charge at a wires endpoints) , causes the speed of the electrons flowing through a wire. The section in this article says that the faster the electrons travel, the charge remains the same. I don't believe this to be true. I have proof in the form of another website, though I can't verify the accuracy of it. Though it is a instructional website, so why would it be wrong? The link: http://www.scottaaronson.com/blog/?p=220 Scroll down to the definition of the different properties of electricity, and you will see "Energy", the last sentence of the paragraph explains something in contrast to the section I mentioned which is in this article. I'm not entirely sure, I don't know a lot about electricity, and the "citation needed" tag seems to be a pretty good identification for false information.BSPolice (talk) 23:21, 7 August 2012 (UTC)

## What is the origin of electric charge?

Antonquery (talk) 03:03, 16 October 2013 (UTC)