Fix A Broken Magnet

Do they stick, repel, or neither?

  • Neither, they just fall apart naturally

    Votes: 0 0.0%

  • Total voters
    5

Thread Starter

MrAl

Joined Jun 17, 2014
11,389
Hello,

This is interesting physics about what happens when a magnet breaks in half.

We have a rectangular magnet, 3 inches long, 1/8 inches thick, 1/2 inches wide, so it forms a long stick shape like a pop-sickle stick but not as round ends.

Ok, so the magnet breaks in half, right near the center of that 3 inch length, and the break is rather jagged, but it fits back together like a 3d puzzle as no small pieces were lost in the breaking process.

So here is the question...
The two pieces fit back together very near perfectly, but do they hold together by themselves (stick together because they are magnets that attract) or do they repel (repel like two magnets that repel each other), or none of the above ?
 

Ramussons

Joined May 3, 2013
1,404
a broken magnet becomes 2 magnets with the original "pole A" intact, the broken / new end becoming the compliment "pole".

N--------------------S becomes N----------S and N----------S and

stick as one N----------SN----------S
 

jpanhalt

Joined Jan 18, 2008
11,087
You need to know how the magnet is polarized. If the N-S poles are at the long ends and it is broken lengthwise (assumed from the description), then I voted that they stick together.

However, if the polarization is perpendicular to the flat face, they will repel. I did the experiment with a kitchen magnet polarized along its shortest dimension:

upload_2018-2-25_6-42-35.png

The two halves repel. That photo is on a smooth counter surface and the separation distance from repulsion is about 6 mm.
 

Thread Starter

MrAl

Joined Jun 17, 2014
11,389
You need to know how the magnet is polarized. If the N-S poles are at the long ends and it is broken lengthwise (assumed from the description), then I voted that they stick together.

However, if the polarization is perpendicular to the flat face, they will repel. I did the experiment with a kitchen magnet polarized along its shortest dimension:

View attachment 146942

The two halves repel. That photo is on a smooth counter surface and the separation distance from repulsion is about 6 mm.
Hi,

I was hoping more people would reply before the right answer came up. You ruined all the fun :)
I also forgot to add the option to choose "both".

Yeah it is funny because on web sites most of the time we see the NS-NS version where they are magnetized end to end, so they always stick. With a face to face magnetization they will repel, and probably also with a cross edge to edge magnetization also they will repel, but i dont have any of those to try.

It's also funny because when the face to face magnetization ones break, the break is jagged but fits together like a puzzle if you carefully align them and hold them together forcibly. Let go and they fly apart though. Epoxy them back together and they form one magnet again, but it's interesting that the epoxy will always be under stress as long as the magnet exists because the two sides will always be trying to pull apart.
 
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