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Message 380541 - Posted: 28 Jul 2006, 9:05:24 UTC

This question relates to science, but it might not be suitable for this forum so sorry if I posted in the wrong place. Oh yeah, this question is also very simple.

OK, I had a problem and I needed to weaken a permanent magnet by great amount, so from research I found that diverting the magnets field apparently works. For example, if you had a horse shoe magnet, touching a piece of metal to both the poles of the magnet(kind of like a short circuit if you think of electricity), reduces the strength of the magnetic field that is left around the magnet. I want to know how much it really reduces the strength, and if it would be able to pick up anything without any physical contact.

I also want to know if there are any other methods of weakening a magnet, blocking it, or, if possible, completely turning it off.

NOTE: I am in a rush so forgive me if some of my information is incorrect.

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Message 380550 - Posted: 28 Jul 2006, 9:17:22 UTC

P.S. Would this weakening method work on super magnets as well?

Also, Would an EXTREMELY weak magnet, or a totally disabled magnet be attracted to other magnets, or would it be neutral?
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Message 380700 - Posted: 28 Jul 2006, 14:34:10 UTC
Last modified: 28 Jul 2006, 14:50:02 UTC

A magnet is a magnet because all the atom's dipole are aligned. You can typically interupt this by tapping it with a hammer or causing the structure to vibrate in a way that allows the atoms to realign. If you could, place a second magnet to the first magnet in opposing directions and start tapping the first magnet. If you do it well, it will weaken, you can only turn it off by completely randomizing the atomic dipole positions within the magnet.
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Message 380710 - Posted: 28 Jul 2006, 14:53:48 UTC

If you are talking about solid magnets (not electromagnetic magnets) a magnet should be able to attract a "dead" magnet because the atoms are still magnetic but not aligned. And for super magnets if you are refering to the electromagnet, then simply turn off the electricty. No need for a hammer.
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Message 381100 - Posted: 28 Jul 2006, 23:49:02 UTC

Thanks sleestak, but I have one last question. Is there a way to make a piece of metal(not magnet) temporarily not attracted to magnets?
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Message 381108 - Posted: 28 Jul 2006, 23:59:18 UTC
Last modified: 29 Jul 2006, 0:00:39 UTC

The only thing I can think of is if you wrap it with wire/magnetwire and run a current through the wire. Current in one direction will attract one end of a dipole but oppose the other. By selecting the proper current in the proper direction you could cancel the effect of an attracting magnet but it would attract the opposite side of the magnet if exposed to it. If that's clear. lol.

You can shield metal from effects of magnets with a Gaussian surface because inside a Gaussian surface, all electromagnetic effects perfectly cancel out. A Gaussian surface can be any ("perfectly") conducting material in any shape enclosing the object. For example, it could be inside a copper sphere or box.

At the moment, that's all I can think of along those lines.
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Message 381305 - Posted: 29 Jul 2006, 3:09:00 UTC
Last modified: 29 Jul 2006, 3:42:55 UTC

When you say conducting material, do you mean electricity conductor?

Would a copper plate weaken the attraction between the magnet and metal if the metal wasn't completely covered?

Basically I need a way of controlling permanent magnets, or the metal they attract without any electricity.

P.S. Would a Gaussian surface be able to stop a magnet being attracted to other magnets?
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Message 381367 - Posted: 29 Jul 2006, 4:39:05 UTC

BTW by super magnet I mean those really strong permanent magnets(they work through your hand). Oh yeah, and the magnets I am talking about are all permanent magnets.

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Message 381498 - Posted: 29 Jul 2006, 10:25:38 UTC

How about a chemical shield?
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Message 381504 - Posted: 29 Jul 2006, 10:40:53 UTC - in response to Message 381305.

When you say conducting material, do you mean electricity conductor?

Would a copper plate weaken the attraction between the magnet and metal if the metal wasn't completely covered?

Basically I need a way of controlling permanent magnets, or the metal they attract without any electricity.

P.S. Would a Gaussian surface be able to stop a magnet being attracted to other magnets?

Can you explain what you are trying to do? It is not possible to block a magnetic field, but you can shield an object by surrounding it with something that is permeable to magnetic fields that the object inside.
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Message 381516 - Posted: 29 Jul 2006, 11:33:46 UTC

There's a material called Mumetal that's works well as a magnetic shield. It's used to wrap electromagnetic reed relays when they're stacked closely together so that the magnetic field of one doesn't affect the relay next to it. Sheets of it are soft and bend easily like thick aluminum foil.
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Message 382985 - Posted: 31 Jul 2006, 7:33:48 UTC - in response to Message 381504.
Last modified: 31 Jul 2006, 7:34:04 UTC

Can you explain what you are trying to do? It is not possible to block a magnetic field, but you can shield an object by surrounding it with something that is (more) permeable to magnetic fields that the object (contained) inside.

I just re-read my post and I appear to have left out several key words. Very sorry, I typed it out in a hurry. Hopefully you all worked out what I was trying to say.
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Message 383817 - Posted: 1 Aug 2006, 1:08:47 UTC - in response to Message 381305.

When you say conducting material, do you mean electricity conductor?

Would a copper plate weaken the attraction between the magnet and metal if the metal wasn't completely covered?

Basically I need a way of controlling permanent magnets, or the metal they attract without any electricity.

P.S. Would a Gaussian surface be able to stop a magnet being attracted to other magnets?


This probably doesn't help you, but heating a magnet up will weaken the field. Get it cherry red or hotter and it won't be much of a magnet anymore.

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Message 407216 - Posted: 26 Aug 2006, 13:31:53 UTC

Is it possible to almost completely shield a material from a magnet without completely covering it? If so, would I need a very good magnet shield?

Stopping a magnet seems hard, is there a way to make the magnet switch poles without physically flipping it over?


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Message 407265 - Posted: 26 Aug 2006, 15:07:03 UTC - in response to Message 407216.

Is it possible to almost completely shield a material from a magnet without completely covering it? If so, would I need a very good magnet shield?

Stopping a magnet seems hard, is there a way to make the magnet switch poles without physically flipping it over?


Only ,I think ,by puting it into a much stronger magnetic field
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Message 407684 - Posted: 27 Aug 2006, 1:43:34 UTC

Ok, say I had a piece of metal, and I wanted to shield it from a magnet. Can some part of the magnet be facing the metal, or does it have to be completely covered? I basically can't completely cover it, and I need to weaken it ALOT.
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Message 407810 - Posted: 27 Aug 2006, 5:06:13 UTC
Last modified: 27 Aug 2006, 5:06:23 UTC

By the way, which material I can find easily would work best as a magnet shield?

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