Talk:Magnetic field

Examples of strong fields

The article seems blocked from editing but the example section ought to include examples of strong fields e.g:

ferrite (ceramic) magnets typically up to 0.35 T (remanent field inside magnet).

Neodymium magnets (and Alnico) up to 1.4 or possibly 1.5 T (remanent field inside magnet).

Electromagnets with iron core, typically up to 2 T.

Superconducting magnets typically used up to 20 T but higher theoretical limit.

Bitter electromagnet up to 37.5 T alone or 45 T in combination with superconducting magnet.

According to https://www.youtube.com/watch?v=-2QaTyDJDEI modern devices based on high-temperature superconductivity can reach 45 T. However a better reference would be needed.150.227.15.253 (talk) 10:47, 10 February 2021 (UTC) See also Superconducting_magnet#History for fields achived by superconducting magnets. 150.227.15.253 (talk) 11:24, 10 February 2021 (UTC)

Non-destructive pulsing can achieve 100 T (or at least that's the goal). https://nationalmaglab.org/education/magnet-academy/learn-the-basics/stories/magnets-from-mini-to-mighty

By explosive compression of magnetic fields transients of at least 200 T can be reached. in fact https://nationalmaglab.org/education/magnet-academy/learn-the-basics/stories/magnets-from-mini-to-mighty reports 1000 T.

The magnetic field on the surface of neutron stars is 10⁴-10¹¹ T.

There might be other astronomical record fields too.150.227.15.253 (talk) 11:21, 1 February 2021 (UTC)

The article is limited to editing by auto-confirmed or confirmed. Your additions look entirely reasonable, but would need reliable sources. Constant314 (talk) 15:18, 1 February 2021 (UTC)

I have given sources, what's wrong with them? Most are links to other Wiki articles. Shouldn't it be possible to refer to other Wiki articles assuming that they have done their job of finding reliable sources? Unfortunately Wiki has several different standards for including references and they are all rather awkward and it's difficult to find a good description of them. Some type of form for entering references would be nice. One could always require more sources but setting the standard requirements to high will just prevent people from making useful additions. A few of my sources are links to webpages of research groups that seem bona fide. People who find that the sources aren't good enough should be welcome to add more sources and to remove sources that become unnecessary by their additions. Errors and doubtful unsupported information need removal of course. Not having a sample list of magnetic field values (or only the Earth's magnetic field) is a larger shortcoming than not having done the job of a major review article.150.227.15.253 (talk) 14:24, 2 February 2021 (UTC)

WP itself is not usable as a source. See WP:CIRCULAR, specifically: Content from a Wikipedia article is not considered reliable unless it is backed up by citing reliable sources. Confirm that these sources support the content, then use them directly. I.e., porting sources over from another article is fine, but just linking to that article as a reference is not. --Elmidae (talk · contribs) 15:15, 2 February 2021 (UTC)

Semi-protected edit request on 2 August 2021

Please administrators, consider seriously eliminating the reference to pseudovectors in the heading of the article. It is unnecessarily misleading. Otherwise move it to the last element of the article as a marginal comment. Peqmeasy (talk) 16:09, 2 August 2021 (UTC)

I agree with removing pseudovectors from the lede. Let's see if anyone else also agrees. Constant314 (talk) 16:33, 2 August 2021 (UTC)

Agree, good idea. --Chetvorno^TALK 17:43, 2 August 2021 (UTC)

In general, the intro text should be rewritten. It's too specialized and confusing. Evgeny (talk) 06:36, 3 August 2021 (UTC)

• Done. Constant314 (talk) 06:51, 3 August 2021 (UTC)

Incorrect animation

The animation titled "The Amperian loop model" is incorrect on the right side. The poles should be moving left-right. The magnetic field should look like the graphic immediately above titled "The magnetic pole model". CEL3939 (talk) 15:06, 8 July 2023 (UTC)

Those aren't poles. That is where the current comes out of the picture and where the current goes back into the picture. Constant314 (talk) 00:15, 9 July 2023 (UTC)

OK, I see that now, thanks! I am used to seeing two poles of opposite sign moving closer together to produce a dipole source, and associated dipole field. CEL3939 (talk) 00:24, 9 July 2023 (UTC)

Vector direction in the Common formulæ table

Several of these are not correct. I tried to fix them before, but they got unfixed. So, I guess we need to discuss them individually.

In a Cylindrical coordinate system the nominal directions are

• Axial, denoted by ${\hat {z}}$
• Radial or polar denoted by ${\hat {\rho }}$ or ${\hat {r}}$
• azimuthal denoted by ${\hat {\theta }}$ or ${\hat {\phi }}$

• Finite beam, infinite wire, infinite cylinder - B does not point in the ${\hat {x}}$ direction which is the radial direction in these figures. The flux points in the azimuthal direction which is typically depicted at ${\hat {\theta }}$ or ${\hat {\phi }}$. To fix, change ${\hat {x}}$ to ${\hat {\theta }}$ and add a note defining ${\hat {\theta }}$.

• Infinite solenoid - B does not point in the ${\hat {x}}$ direction. It points axially. To fix, change ${\hat {x}}$ to ${\hat {z}}$ and add a note defining ${\hat {z}}$.

• Solenoid - ${\hat {x}}$ is not depicted. The flux points axially. To fix, change ${\hat {x}}$ to ${\hat {z}}$ and add a note defining ${\hat {z}}$.

• Circular loop - uses x instead of z, but does not need to be fixed.

• Circular toroid - OK.

• Magnetic dipole - This is actually just a circular loop with magnetic dipole moment specified instead of current. The formula implies an abrupt change of direction upon crossing the equitorial plane. To fix replace $x^{3}$ with ${|x|}^{3}$.

Constant314 (talk) 21:01, 17 September 2024 (UTC)