Talk:Ampère's circuital law

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This article should correctly be entitled 'Ampère's Circuital Law'.

Ampère's Law is a different law relating to the magnetic force that acts between two loops of electric current. (203.115.188.254 08:02, 18 February 2007 (UTC))

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[edit] Title

First of all, it's time to put this article under its correct title Ampère's Circuital Law. Ampère's Law is a different law altogether concerning the force between elements of electric current. --unsigned

Ok, but somebody needs to make an article about Ampere's Law, instead of leaving it as a redirect to here. I'd do it myself, but I am not versed in the technology (I got here from clicking on "Random Article") -- trlkly 09:37, 27 July 2007 (UTC)


[edit] Displacement Current

It is a common myth, circulated in the secondary literature, that Maxwell conceived of displacement current in connection with an electric capacitor circuit. This is quite simply not so. Anybody who has studied his papers of 1861, 1865, and 1873 will find absolutely no evidence of the capacitor circuit being in any way involved in his conception of displacement current. Displacement current first appears in his 1861 paper On Physical Lines of Forcein connection with linear stress and elasticity in the solid which he considered to be the luminiferous medium. (125.24.193.126 16:17, 13 April 2007 (UTC))

[edit] Alternate form of Ampère's Circuital Law

Why is there no mention of \oint_{l} \vec B\cdot d\vec l=\mu_0I on this page? --70.81.118.123 06:23, 5 December 2005 (UTC)

Was here,but someone must have deleted it.--85.103.37.24 10:16, 19 January 2006 (UTC)

I put it back, they're integrated now. This page needs *work* and the terminolgy is all messed up. Particularly confusing is the difference between B and H. Not to mention that H is magnetic field density on the Maxwell's equations page, and magnetic flux density on this page.. I'm too confused to fix more. Fresheneesz 22:51, 3 February 2006 (UTC)

H is not magnetic flux density.....B is magnetic flux density..H is magnetic flux intensity..similar what electric field is in electrostatics...[vijin]

[edit] whats dA

What's da in the first formula?

I'd vote for an infintesimal part of the surface S. This is a surface itself. In French, the word "aire" is used for surface. I suggest to change da for ds.

I added the defintion from the page Maxwell's equations. This page needs to define ALL its variables - its in poor shape. Fresheneesz 22:59, 3 February 2006 (UTC)

[edit] Bad Units for vector D

I noticed that the page defines

\vec{D} \ = \ \varepsilon \vec{E}

as having units of A/m2. The units should in fact be coulombs/m2. When you do:

{\mathrm{d} \over \mathrm{d}t} \iint_S \vec{D} \cdot \mathrm{d} \vec{A}

the result of the integral is in coulombs. Taking the derivative with respect to time yields coulombs/sec or amperes. This is what we want, since

\oint_C \vec{H} \cdot \mathrm{d}\vec{l}

gives a current, as H has units of A/M and integrating that over length results in Amperes.

I mention this here so that someone else can change it. I am new to Wikipedia and don't want to screw up the original article. UPDATE: I HAVE CORRECTED THIS IN THE ARTICLE.

[edit] Ampere do what??

Ampère not get any expression for magnectic field from a elementary current... He works with distance-force between current elements I_1 d\vec {\ell }_1 and I_2 d\vec {\ell }_2...


d^2\vec{F_{21}^A} = - \frac{\mu _0 }{4\pi }I_1 I_2 \frac{\hat {r}_{12} }{r_{12}^2 }[2(d\vec {\ell }_1 \cdot d\vec {\ell }_2) - 3({\hat {r}_{12} \cdot d\vec {\ell }_1 })({\hat {r}_{12} \cdot d\vec {\ell }_2 })] = - d^2\vec{F_{12}^A}


PLASE SEE HISTORIC REFS. (and remember also that magnectic field was a new conception only applied after Maxwell's days).

See for ex. R.A.R. Tricker, "Early Electrodynamics - The First Law of Circulation", 1965.

[edit] Template:Electromagnetism vs Template:Electromagnetism2

I have thought for a while that the electromagnetism template is too long. I feel it gives a better overview of the subject if all of the main topics can be seen together. I created a new template and gave an explanation on the old template talk page, however I don't think many people are watching that page.

I have modified this article to demonstrate the new template and I would appreciate people's thoughts on it: constructive criticism, arguments for or against the change, suggestions for different layouts, etc.

To see an example of a similar template style, check out Template:Thermodynamic_equations. This example expands the sublist associated with the main topic article currently being viewed, then has a separate template for each main topic once you are viewing articles within that topic. My personal preference (at least for electromagnetism) would be to remain with just one template and expand the main topic sublist for all articles associated with that topic.--DJIndica 16:40, 6 November 2007 (UTC)

[edit] Ampere's force law

Hello! I don't think Ampere's force law belongs in an article on Ampere's circuital law. They're named after the same person, but they're not the same law, and the title of the article was chosen specifically for that reason.

What I propose doing is:

  • Putting the information here into Lorentz force, since Ampere's force law and the Lorentz force law are logically equivalent, and Ampere's force law is just as often referred to as a "form of the Lorentz force law".
  • Create a redirect page at Ampere's force law, redirecting to Lorentz force.
  • Put a disambiguating-type note at the top of this article.

Any thoughts? --Steve (talk) 04:16, 20 February 2008 (UTC)

Done. I should amend what I said before: Ampere's force law (as defined here) is not equivalent to the Lorentz force law, but is the combination of that and the Biot-Savart law. I wasn't clear on the definition before, and in what I wrote above, I was confusing it with the Laplace force (which, by the way, I also added into the Lorentz force article). Regardless, the section is much more at home in Lorentz force than it was here, and I tried to explain there exactly how it fits in. But it would also be appropriate as a separate article, if someone feels strongly about it. --Steve (talk) 00:08, 21 February 2008 (UTC)

I have taken up your suggestion for a separate article and put it under Ampere's force law. I believe that is good policy because this law underlies the definition of the ampere, and should be made easy to find. Also, as the references indicate, the term "Ampere's law" often refers to this force law. Links are added to Ampere's circuital law and Lorentz force and Biot-Savart law.

Brews ohare (talk) 17:34, 21 February 2008 (UTC)