B Simple experiment with magnets

I made a little experiment with magnets.
I got two small bars of magnets. They obey the usual attraction-repulsion rules by approaching their faces together in various permutation.

Accidentally, one of them is broken into two unequal pieces. When I managed to put the two broken pieces side by side using the attraction force and then approaching them to the other intact magnet, I found that one side got repulsed and the other is attracted to the intact magnet.

When I managed to reverse the direction of the broken pieces in order to maintain the homogeneous attraction with the intact magnet, the two pieces got repulsed from each other.

How to explain this?
Does it mean that the intact magnet is under a side to side repulsion force between its components?
What happened at the moment of the break?

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davenn

Gold Member
When I managed to reverse the direction of the broken pieces in order to maintain the homogeneous attraction with the intact magnet, the two pieces got repulsed from each other.

of course ... do you not realise than when you break a bar magnet you end up with 2 separate bar magnets ?

Now, when I approach the broken magnet in your drawing to an intact magnet, a repulsion force happened as shown.

How to explain this?

Wes Tausend

Gold Member
Adel, if your diagram is accurate, this is a very interesting proposition. The outcome seems impossible to me.

One might think that, if the smaller broken piece is small enough, that this now entire weak magnetic piece would totally assume either magnetic pole property of the more powerful magnets by close proximity to them. This is what I believe should happen if a small non-magnetized piece of iron bar is subjected to the field of one, or the other, pole of a larger intact bar magnet. In this case, it seems the small broken piece should not be repelled by the opposite pole of an adjacent bar magnet, but merely be attracted, acting non-broken.

I have some small bar magnets that I used to model atoms to teach myself simple atomic theory. I'm reluctant to break one of them, but I devised a similar experiment to yours while leaving them intact.

I was unable to repeat your repulsion effect by adding a small ball bearing to the end of one of a pair of bar magnets. If my bar magnets are pre-aligned to lay beside one another in an attractive N/S arrangement, adding a neutral ball bearing to one end does not cause any repulsion, but rather my neutral ball bearing 'chunk' appears to become equally, and centrally, attracted by both magnets. In other words, I assume my formerly neutral ball bearing temporarily becomes it's own spherical shaped bar magnet and fits comfortably in place, properly N/S aligned between the other two main magnets. For some reason, this is apparently not the case with your small, broken, weak magnetic chunk.

I hope you are able to solve this, or somebody else has some additional insight on your experiment. Can you cut another bar magnet in roughly equal lengths and try that, for instance? Any other ideas, anyone?

Wes

Adel, if your diagram is accurate, this is a very interesting proposition. The outcome seems impossible to me.
Here is the experiment in action.
The first picture shows the broken pieces put together side by side. I stick a small yellow paper in one side and a blue paper on the opposite side (the color does not imply the polarity of the magnet). I assume that this should be the original shape of the magnet before the break.

Notice, however, that there is a minimal tilt. But, this is due to the fact that a little piece is missing at the broken edge which caused this little malalignment.

Now approach this broken magnet to an intact one.

The picture speaks for itself. The original orientation of the pieces is lost and the small piece flies away into the edge of the magnet.

Now in order to maintain the broken pieces on top of the intact magnet in equilibrium, I had to turn the small piece upside down. See this;

But notice, that there is small distance separating the broken pieces, as expected from the repulsion forces.
This made me think that the original orientation of the magnet is not what is shown in the first two pictures. It is the last one. Which means that there could be a repulsion force between the components of any magnet and only the electric force between the atoms that makes the magnet a compact solid body. Once the electric force is breached by whatever external deformation, the magnet is ripped into pieces.

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ChemAir

Gold Member
Would this make sense if the blue and yellow sides are the poles, rather than the ends?

Wes Tausend

Gold Member

Thanks for getting back and your extra effort to produce photo's.

I still don't see why. Broken magnetic pieces should still retain the original polarity directions as far as I understand. There would be a slight disparity in strength between the larger broken piece and the smaller, but I am not quite sure your result is what I should expect.

It's possible the short piece see 'too much' of one pole of the most powerful intact magnet, or something, since both short ends are nearest one end of the intact magnet.

Is it possible you have reversed the blue and yellow sides of the small piece? Or do the pieces clearly fit together correctly as your present blue-blue configuration, minus a well-defined missing sliver?

Wes

Nik_2213

A stronger magnet may attract a weaker one 'the wrong way around', but not as well.
IIRC, related to coercivity.

Benbenben

Now, when I approach the broken magnet in your drawing to an intact magnet, a repulsion force happened as shown.

View attachment 241280
How to explain this?
The assumption about the orientation of magnitization is incorrect. From what is shown, the north and south poles are probably aligned with the largest faces of the blocks. ,
The action makes sense if 'up' is north (or south) and 'down' is south (or north). When the two broken pieces are put together side by side away from the other magnet, the orientation will be with opposite poles facing up to be stable....so the tape was applied to the magnets with the same color on opposite poles. The tilt is likely due in large part due to nonalignment with original break.
When the two pieces with opposite poles facing up are places on the whole larger magnet with only one pole upward facing, the piece nonaligned is repelled.

The assumption about the orientation of magnitization is incorrect. From what is shown, the north and south poles are probably aligned with the largest faces of the blocks.
That was not my assumption anyway.
I have also reached to the same conclusion; that is the pole is assigned to the larger face of the magnet too.

This solves the first problem of the thread but does not solve the second problem mentioned in the thread no.1 and explained in no.5.
If the same poles of the magnet at the microscopic level are facing to one direction, then it must not be stable. This is due to a repulsion force between its components. And because the magnet must have a pole facing one direction and the other pole facing the other direction, by definition of the magnet, then any magnet should be unstable at the microscopic level. It is similar to try making a pen stands on its tip; it is a solution but unstable solution which is easily broken by any little perturbation made on the initial condition.

sophiecentaur

Gold Member
If you replace the single broken magnet with many segments then I would expect the pieces to align themselves more or less with the field of the whole magnet - the same as happens with iron filings (which become tiny induced magnets, sticking nose to tail from the N pole to the S pole in that familiar pattern).
An unbroken magnet will experience a torque which would make it take up the shape of the iron filings but the rigidity stops this happening and you are left with a stronger field at the double poles.

Benbenben

That was not my assumption anyway.
I have also reached to the same conclusion; that is the pole is assigned to the larger face of the magnet too.

This solves the first problem of the thread but does not solve the second problem mentioned in the thread no.1 and explained in no.5.
If the same poles of the magnet at the microscopic level are facing to one direction, then it must not be stable.
There is no 'problem' unsolved with what you refer to as 'the second problem'. Numbers of individual small Magnets at the single domain level (as with larger individual magnets) do not typically self assemble into a composite large magnets with all small magnets universally aligned developing two distinct opposite poles.
Why? Because it is far less stable than arrangements where the
magnetic circuit is shorter and has far less air gap.
Just spend some time playing around with a good number small magnets. It will quickly become clear that for individual magnets with poles all facing the same direction, it is far easier to stack magnets up the direction of the axis of the poles than it is to attempt to place two magnets poles alligned in parallel immediately side by side.
In short, macro assemblies with well aligned poles of micro constituent domains are not stable as a pile of grains.

"Simple experiment with magnets"

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