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  4. Sudden polarity reversal in opposing permanent magnets?
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Sudden polarity reversal in opposing permanent magnets?

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Offline sw20 (OP)

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Sudden polarity reversal in opposing permanent magnets?
« on: 22/05/2020 20:09:14 »
Hi all,

I'm working with a pair of multi-pole neodymium ring magnets (rated ~119lbF, McMaster-Carr part number 2494N17) and finding that if the opposing poles are forced together, with the magnets in alignment, that at very close range (may be a millimeter or two apart?) the two magnets will suddenly snap together as if one has reversed polarity. There is NO electric current involved, but the only resources I am finding about this phenomenom are related to electromagnets and induced magnetism.

Can anyone point me to a source explaining what's happening?

Thank you!
« Last Edit: 22/05/2020 20:47:54 by sw20 »
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Offline evan_au

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Re: Sudden polarity reversal in opposing permanent magnets?
« Reply #1 on: 22/05/2020 23:12:30 »
As they are multi-pole magnets (6 North+6 South on the same side), there will be a rotational force to bring the North pole of one magnet into line with the South pole of the other magnet.
- Since this configuration causes strong attraction, the two magnets will move together (away from your fingers), and you may not feel them rotating by 30° to align.

I suggest that you place a mark on both magnets when they are together (attractive): There are several points, 60° apart where they will be aligned...
- Then separate them
- Press them together when they are misaligned (repulsive)
- When they snap together, see if they are now aligned.

 
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Offline sw20 (OP)

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Re: Sudden polarity reversal in opposing permanent magnets?
« Reply #2 on: 22/05/2020 23:27:35 »
I have tried that previously, and just did it again many times for the sake of confirming - they will snap together at any rotational alignment. I notice that it is more difficult (requires more force) in some alignments, but the apparent polarity change happens regardless. It's weird!
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Offline Petrochemicals

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Re: Sudden polarity reversal in opposing permanent magnets?
« Reply #3 on: 24/05/2020 16:39:51 »
Is magnetic force alteratable or does it have to be diffused ?

Edit:

"Polarity of magnetic force" for clarity
« Last Edit: 24/05/2020 23:09:50 by Petrochemicals »
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Offline sw20 (OP)

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Re: Sudden polarity reversal in opposing permanent magnets?
« Reply #4 on: 24/05/2020 21:29:18 »
Petrochemicals, I'm not following your question. I'm working with two permanent magnets, so not alterable in any way.
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Re: Sudden polarity reversal in opposing permanent magnets?
« Reply #5 on: 24/05/2020 22:15:37 »

Quote from: sw20 on 24/05/2020 21:29:18
Petrochemicals, I'm not following your question. I'm working with two permanent magnets, so not alterable in any way.
Quote from: sw20 on 22/05/2020 20:09:14
if the opposing poles are forced together, with the magnets in alignment, that at very close range (may be a millimeter or two apart?) the two magnets will suddenly snap together as if one has reversed polarity.

It seems to be what you are asking , either the magnets (or at least one) is reversing polarity, or somehow dissipating its force?
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Offline evan_au

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Re: Sudden polarity reversal in opposing permanent magnets?
« Reply #6 on: 24/05/2020 23:02:09 »
Quote from: OP
Sudden polarity reversal in opposing permanent magnets?
As they are two identical magnets from the factory, I do not think that one is suddenly reversing polarity.

Especially since, after you separate them, they still have a strong repulsion at certain angles. It's not like one suddenly got demagnetised.
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Re: Sudden polarity reversal in opposing permanent magnets?
« Reply #7 on: 25/05/2020 00:30:05 »
With you now. Yes it's clear there is no permanent polarity reversal or full demagnetisation.

Situation appears like a temporary one, but I agree that does not make sense since they are identical factory-produced magnets. Thus the original post.
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Offline hamdani yusuf

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Re: Sudden polarity reversal in opposing permanent magnets?
« Reply #8 on: 27/05/2020 14:11:47 »
Can you show a diagram for this experiment?
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Tags: magnet  / magnets  / magnetism  / polarity  / polarity reversal  / neodymium 
 

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