If I had a horseshoe-shaped magnet and bent it so that the ends touched – would it lose its magnetism?

party_pants said:

If I had a horseshoe-shaped magnet and bent it so that the ends touched – would it lose its magnetism?

Horeshoe magnets always came with a bar that connected both ends?

roughbarked said:

party_pants said:

If I had a horseshoe-shaped magnet and bent it so that the ends touched – would it lose its magnetism?

Horeshoe magnets always came with a bar that connected both ends?

yes, a keeper. retains magnetism whilst being paramagnetic itself. if you connected the ends it wouldn’t lose its magnetism. maybe.

ChrispenEvan said:

roughbarked said:

party_pants said:

If I had a horseshoe-shaped magnet and bent it so that the ends touched – would it lose its magnetism?

Horeshoe magnets always came with a bar that connected both ends?

yes, a keeper. retains magnetism whilst being paramagnetic itself. if you connected the ends it wouldn’t lose its magnetism. maybe.

the reason i say this, and after a bit of thought, is that there is no defined point where N turns to S. cut a horseshoe magnet in half and you will still have a N end and a S end.

roughbarked said:

party_pants said:

If I had a horseshoe-shaped magnet and bent it so that the ends touched – would it lose its magnetism?

Horeshoe magnets always came with a bar that connected both ends?

Didn’t know hores used hoes. Magnets will lose their magnetism by varuios ways but the strength is retained longer by connecting north to south. Bar magnets are stored with north south touching rather than putting two like poles close together.

roughbarked said:

roughbarked said:

party_pants said:

If I had a horseshoe-shaped magnet and bent it so that the ends touched – would it lose its magnetism?

Horeshoe magnets always came with a bar that connected both ends?

Didn’t know hores used hoes. Magnets will lose their magnetism by varuios ways but the strength is retained longer by connecting north to south. Bar magnets are stored with north south touching rather than putting two like poles close together.

Bar magnets usually come in a set of two with the ends connected.

>yes, a keeper. retains magnetism whilst being paramagnetic itself. if you connected the ends it wouldn’t lose its magnetism. maybe.

cuddle, so the attraction doesn’t fade

party_pants said:

If I had a horseshoe-shaped magnet and bent it so that the ends touched – would it lose its magnetism?

Yes, over time. I have a very old book about magnetism that gives an equation for the rate at which permanent magnets lose their magnetism. The closer a north pole is to a south pole the faster it loses its magmetism.

The equation also compared the rate of loss of magnetism between a horseshoe magnet with a soft iron “keeper” connecting the poles and a horseshoe magnet without a keeper. Until I read that, I had never bothered putting the keeper back. Now I always do. A horseshoe magnet loses its power very much faster (from memory about ten times as fast) without a keeper.

This book. From 1963. I thought it was going to be a boring topic. But it can really be extremely interesting.

mollwollfumble said:

party_pants said:

If I had a horseshoe-shaped magnet and bent it so that the ends touched – would it lose its magnetism?

Yes, over time. I have a very old book about magnetism that gives an equation for the rate at which permanent magnets lose their magnetism. The closer a north pole is to a south pole the faster it loses its magmetism.

The equation also compared the rate of loss of magnetism between a horseshoe magnet with a soft iron “keeper” connecting the poles and a horseshoe magnet without a keeper. Until I read that, I had never bothered putting the keeper back. Now I always do. A horseshoe magnet loses its power very much faster (from memory about ten times as fast) without a keeper.

This book. From 1963. I thought it was going to be a boring topic. But it can really be extremely interesting.

http://www.penguinfirsteditions.com/pel/A481.jpg!

OK, if it comes from a battered Pelican book, priced in old money, I guess it must be right.

Nonetheless, it seems strange that magnet life is reduced by bringing the N and S poles closer together, but greatly increased if you actually connect them.

Any idea how that works?

party_pants said:

If I had a horseshoe-shaped magnet and bent it so that the ends touched – would it lose its magnetism?

Yes.

Peak Warming Man said:

party_pants said:

If I had a horseshoe-shaped magnet and bent it so that the ends touched – would it lose its magnetism?

Yes.

I hope you have a battered paperback reference to support that statement.

The Rev Dodgson said:

Peak Warming Man said:

party_pants said:

If I had a horseshoe-shaped magnet and bent it so that the ends touched – would it lose its magnetism?

Yes.

I hope you have a battered paperback reference to support that statement.

It’s just the vibe but the iron filing map of the magnet after the two poles are brought into contact would be interesting.

Peak Warming Man said:

It’s just the vibe but the iron filing map of the magnet after the two poles are brought into contact would be interesting.

Well, exceedingly boring, but

http://slideplayer.com/slide/5777330/

you want air gap bit so fast forward or whatever.

ChrispenEvan said:

http://slideplayer.com/slide/5777330/

you want air gap bit so fast forward or whatever.

so if my understanding of that is right placing the N and S of a Horseshoe magnet together would be the same as using a keeper and thus the magnet will last longer. all magnets “run down” after some time.

ChrispenEvan said:

so if my understanding of that is right placing the N and S of a Horseshoe magnet together would be the same as using a keeper and thus the magnet will last longer. all magnets “run down” after some time.

I don’t think it’s the same.

Peak Warming Man said:

ChrispenEvan said:

so if my understanding of that is right placing the N and S of a Horseshoe magnet together would be the same as using a keeper and thus the magnet will last longer. all magnets “run down” after some time.

I don’t think it’s the same.

that graphic said it is.

might have to call for an experiment….

ChrispenEvan said:

Peak Warming Man said:

ChrispenEvan said:

so if my understanding of that is right placing the N and S of a Horseshoe magnet together would be the same as using a keeper and thus the magnet will last longer. all magnets “run down” after some time.

I don’t think it’s the same.

that graphic said it is.

That’s two horseshoes with N to S touching on both.

Peak Warming Man said:

ChrispenEvan said:

Peak Warming Man said:

I don’t think it’s the same.

that graphic said it is.

That’s two horseshoes with N to S touching on both.

LOL, and the difference is?

On the subject of magnetism…

Consider a long solenoid, with some current flowing. Inside the solenoid, there’s a fairly constant magnetic field, B, along the entire length, which can be easily calculated from the number of turns of wire, diameter of the solenoid, and the current flowing. The magnetic field outside the solenoid, about half way along the solenoid’s length is zero or negligible. This can be demonstrated by passing a beam of electrons past the solenoid and observing the deflection with and without current flow: there’s none.

If the beam of electrons impinges on a double-slit setup, the diffraction pattern changes position according to whether current is flowing in the solenoid: the phase of the electron beam is affected by the magnetic vector potential A, despite the facts that (a) A is not a physical property, and (b) the electrons’ phase is imaginary.

This is the best-known example of the Aharonov–Bohm effect.

ChrispenEvan said:

so if my understanding of that is right placing the N and S of a Horseshoe magnet together would be the same as using a keeper and thus the magnet will last longer. all magnets “run down” after some time.

Isn’t that what I said from the beginning of this affair?

roughbarked said:

ChrispenEvan said:

so if my understanding of that is right placing the N and S of a Horseshoe magnet together would be the same as using a keeper and thus the magnet will last longer. all magnets “run down” after some time.

Isn’t that what I said from the beginning of this affair?

No, you asked a question. Plus you never explained anything.

ChrispenEvan said:

ChrispenEvan said:

http://slideplayer.com/slide/5777330/

you want air gap bit so fast forward or whatever.

It’s not really battered enough, but it makes sense anyway I suppose.

The Rev Dodgson said:

ChrispenEvan said:

ChrispenEvan said:

http://slideplayer.com/slide/5777330/

you want air gap bit so fast forward or whatever.

It’s not really battered enough, but it makes sense anyway I suppose.

Magnetite seems to last pretty well without “keepers” in rocks. I mean, at least hundreds of millions of years (at least) seems reasonably like lasting to me.

Michael V said:

The Rev Dodgson said:

ChrispenEvan said:

It’s not really battered enough, but it makes sense anyway I suppose.

Magnetite seems to last pretty well without “keepers” in rocks. I mean, at least hundreds of millions of years (at least) seems reasonably like lasting to me.

Wiki

A magnet keeper, also known historically as an armature, is a paramagnetic bar made from soft iron or steel, which is placed across the poles of a permanent magnet to help preserve the strength of the magnet by completing the magnetic circuit; it is important for magnets that have a low magnetic coercivity, such as alnico magnets.

Keepers also have a useful safety function, as they stop external metal being attracted to the magnet.

Most magnets do not need a keeper, only those with low coercivity, meaning that they are easily susceptible to stray fields.

A magnet can be considered as the sum of many little magnetic domains, which may only be a few microns or smaller in size. Each domain carries its own small magnetic field, which can point in any direction. When all the domains are pointing in the same direction, the fields add, yielding a strong magnet. When these all point in random directions, they cancel each other, and the net magnetic field is zero.

In magnets with low coercivity, the direction in which the magnetic domains are pointing is easily swayed by external fields, such as the Earth’s magnetic field or perhaps by the stray fields caused by flowing currents in a nearby electrical circuit. Given enough time, such magnets may find their domains randomly oriented, and hence their net magnetization greatly weakened. A keeper for low-coercivity magnets is just a strong permanent magnet that keeps all the domains pointing the same way and realigns those that may have gone astray.

coercivity

Fine. Baffle me with magicians jargon.

Michael V said:

coercivity

Fine. Baffle me with magicians jargon.

the resistance of a magnetic material to changes in magnetization, equivalent to the field intensity necessary to demagnetize the fully magnetized material.

ChrispenEvan said:

Michael V said:

coercivity

Fine. Baffle me with magicians jargon.

the resistance of a magnetic material to changes in magnetization, equivalent to the field intensity necessary to demagnetize the fully magnetized material.

Yeah, I’m just reading about that now. I have yet to look for the coercivity of magnetite.

Not much out there I can understand about the coercivity of magnetite.

had a read re coercivity in wiki, then ended up in…quite interesting.

https://en.wikipedia.org/wiki/Magnetic_bearing

ChrispenEvan said:

roughbarked said:

ChrispenEvan said:

so if my understanding of that is right placing the N and S of a Horseshoe magnet together would be the same as using a keeper and thus the magnet will last longer. all magnets “run down” after some time.

Isn’t that what I said from the beginning of this affair?

No, you asked a question. Plus you never explained anything.

Why would I bother explaining something that most of you should know quite well?

I’ve been repeatedly told that I know nothing or that I’m either totally incorrect or way off the beam.

Yet in many instances nobody else explains why. If I pose an answer to look like a question then surely by asking yourself the same question you will believe that you thought of the answer and therefore had no reason to attack me.

I’ll ask another question. How to demagnetize a magnet?

roughbarked said:

ChrispenEvan said:

roughbarked said:

Isn’t that what I said from the beginning of this affair?

No, you asked a question. Plus you never explained anything.

Why would I bother explaining something that most of you should know quite well?

I’ve been repeatedly told that I know nothing or that I’m either totally incorrect or way off the beam.

Yet in many instances nobody else explains why. If I pose an answer to look like a question then surely by asking yourself the same question you will believe that you thought of the answer and therefore had no reason to attack me.

I’ll ask another question. How to demagnetize a magnet?

LOL. You asked a question not answered one. Don’t try this bullshit it doesn’t work with me. heat it past its curie point for one.

ChrispenEvan said:

roughbarked said:

ChrispenEvan said:

No, you asked a question. Plus you never explained anything.

Why would I bother explaining something that most of you should know quite well?

I’ve been repeatedly told that I know nothing or that I’m either totally incorrect or way off the beam.

Yet in many instances nobody else explains why. If I pose an answer to look like a question then surely by asking yourself the same question you will believe that you thought of the answer and therefore had no reason to attack me.

I’ll ask another question. How to demagnetize a magnet?

LOL. You asked a question not answered one. Don’t try this bullshit it doesn’t work with me. heat it past its curie point for one.

It may have sounded like a question and looked like a question but it wasn’t and you knew it. So stop attempting to not look like a badarse bully.

roughbarked said:

ChrispenEvan said:

roughbarked said:

Why would I bother explaining something that most of you should know quite well?

I’ve been repeatedly told that I know nothing or that I’m either totally incorrect or way off the beam.

Yet in many instances nobody else explains why. If I pose an answer to look like a question then surely by asking yourself the same question you will believe that you thought of the answer and therefore had no reason to attack me.

I’ll ask another question. How to demagnetize a magnet?

LOL. You asked a question not answered one. Don’t try this bullshit it doesn’t work with me. heat it past its curie point for one.

It may have sounded like a question and looked like a question but it wasn’t and you knew it. So stop attempting to not look like a badarse bully.

So it walked like a duck and talked like a duck but it wasn’t a duck?. You stop trying to sound as if you know all this stuff before anyone else just because you post some cryptic shit. So maybe if you pulled your head in i wouldn’t have to do it for you.

ChrispenEvan said:

roughbarked said:

ChrispenEvan said:

LOL. You asked a question not answered one. Don’t try this bullshit it doesn’t work with me. heat it past its curie point for one.

It may have sounded like a question and looked like a question but it wasn’t and you knew it. So stop attempting to not look like a badarse bully.

So it walked like a duck and talked like a duck but it wasn’t a duck?. You stop trying to sound as if you know all this stuff before anyone else just because you post some cryptic shit. So maybe if you pulled your head in i wouldn’t have to do it for you.

You still haven’t really talked about how a magnet can be demagnetized by its own magnetic field.

You spend most of your time trying to put others below you.

roughbarked said:

ChrispenEvan said:

roughbarked said:

It may have sounded like a question and looked like a question but it wasn’t and you knew it. So stop attempting to not look like a badarse bully.

So it walked like a duck and talked like a duck but it wasn’t a duck?. You stop trying to sound as if you know all this stuff before anyone else just because you post some cryptic shit. So maybe if you pulled your head in i wouldn’t have to do it for you.

You still haven’t really talked about how a magnet can be demagnetized by its own magnetic field.

Can it? and where is the reference in this thread where i had to?

ChrispenEvan said:

roughbarked said:

ChrispenEvan said:

So it walked like a duck and talked like a duck but it wasn’t a duck?. You stop trying to sound as if you know all this stuff before anyone else just because you post some cryptic shit. So maybe if you pulled your head in i wouldn’t have to do it for you.

You still haven’t really talked about how a magnet can be demagnetized by its own magnetic field.

Can it? and where is the reference in this thread where i had to?

No it cannot but the original question was framed this way.

ChrispenEvan said:

roughbarked said:

ChrispenEvan said:

LOL. You asked a question not answered one. Don’t try this bullshit it doesn’t work with me. heat it past its curie point for one.

It may have sounded like a question and looked like a question but it wasn’t and you knew it. So stop attempting to not look like a badarse bully.

So it walked like a duck and talked like a duck but it wasn’t a duck?. You stop trying to sound as if you know all this stuff before anyone else just because you post some cryptic shit. So maybe if you pulled your head in i wouldn’t have to do it for you.

I didn’t say I know any stuff before anyone else.

I only pointed out that I mentioned that I knew stuff about magnets, early on.
I still reckon that you are using bullying because you didn’t actually know. The simple answer was no.
All magnets will lose their magnetism eventually as the electrons lose their alignment. The keeper as you rightly noticed, keeps the north and south poles connected to slow this process down.

roughbarked said:

ChrispenEvan said:

roughbarked said:

It may have sounded like a question and looked like a question but it wasn’t and you knew it. So stop attempting to not look like a badarse bully.

So it walked like a duck and talked like a duck but it wasn’t a duck?. You stop trying to sound as if you know all this stuff before anyone else just because you post some cryptic shit. So maybe if you pulled your head in i wouldn’t have to do it for you.

I didn’t say I know any stuff before anyone else.

I only pointed out that I mentioned that I knew stuff about magnets, early on.
I still reckon that you are using bullying because you didn’t actually know. The simple answer was no.
All magnets will lose their magnetism eventually as the electrons lose their alignment. The keeper as you rightly noticed, keeps the north and south poles connected to slow this process down.

Good to see you have now done some reading. Nowhere did I say I knew. I look for pages that may explain things. Then I form an opinion. I even say “maybe” etc. If you actually know then why not post that info? Coming in later and saying you know comes across as bullshit on your part. And your “why should i bother explaining things…” etc doesn’t wash. But this is typical of you. The ancients know, shit.

ChrispenEvan said:

roughbarked said:

ChrispenEvan said:

So it walked like a duck and talked like a duck but it wasn’t a duck?. You stop trying to sound as if you know all this stuff before anyone else just because you post some cryptic shit. So maybe if you pulled your head in i wouldn’t have to do it for you.

I didn’t say I know any stuff before anyone else.

I only pointed out that I mentioned that I knew stuff about magnets, early on.
I still reckon that you are using bullying because you didn’t actually know. The simple answer was no.
All magnets will lose their magnetism eventually as the electrons lose their alignment. The keeper as you rightly noticed, keeps the north and south poles connected to slow this process down.

Good to see you have now done some reading. Nowhere did I say I knew. I look for pages that may explain things. Then I form an opinion. I even say “maybe” etc. If you actually know then why not post that info? Coming in later and saying you know comes across as bullshit on your part. And your “why should i bother explaining things…” etc doesn’t wash. But this is typical of you. The ancients know, shit.

maybe look up magnetic domains.

ChrispenEvan said:

roughbarked said:

ChrispenEvan said:

So it walked like a duck and talked like a duck but it wasn’t a duck?. You stop trying to sound as if you know all this stuff before anyone else just because you post some cryptic shit. So maybe if you pulled your head in i wouldn’t have to do it for you.

I didn’t say I know any stuff before anyone else.

I only pointed out that I mentioned that I knew stuff about magnets, early on.
I still reckon that you are using bullying because you didn’t actually know. The simple answer was no.
All magnets will lose their magnetism eventually as the electrons lose their alignment. The keeper as you rightly noticed, keeps the north and south poles connected to slow this process down.

Good to see you have now done some reading. Nowhere did I say I knew. I look for pages that may explain things. Then I form an opinion. I even say “maybe” etc. If you actually know then why not post that info? Coming in later and saying you know comes across as bullshit on your part. And your “why should i bother explaining things…” etc doesn’t wash. But this is typical of you. The ancients know, shit.

I don’t care how I come across to you. You are a bully and I treat you that way. Always have. If you can prove you aren’t, I’ll change my game.

I didn’t have to read about magnets any more than i didn’t have to read about metrics when we adopted the metric system. I was already doing all this stuff with watchmaking. But I’ve been interested in magnets since I was a little kid.

When did we go metric?

Found it…1974.

and buffy said:

When did we go metric?

between 1970 and 1988

buffy said:

When did we go metric?

Metric money came in in 1966.

roughbarked said:

ChrispenEvan said:

roughbarked said:

I didn’t say I know any stuff before anyone else.

I only pointed out that I mentioned that I knew stuff about magnets, early on.
I still reckon that you are using bullying because you didn’t actually know. The simple answer was no.
All magnets will lose their magnetism eventually as the electrons lose their alignment. The keeper as you rightly noticed, keeps the north and south poles connected to slow this process down.

Good to see you have now done some reading. Nowhere did I say I knew. I look for pages that may explain things. Then I form an opinion. I even say “maybe” etc. If you actually know then why not post that info? Coming in later and saying you know comes across as bullshit on your part. And your “why should i bother explaining things…” etc doesn’t wash. But this is typical of you. The ancients know, shit.

I don’t care how I come across to you. You are a bully and I treat you that way. Always have. If you can prove you aren’t, I’ll change my game.

LOL. You aren’t just posting for me but to try and put up info for everyone who reads this forum. To limit it to me shows you just don’t get it.

buffy said:

When did we go metric?

Well after I became an apprentice watchmaker. I finished mid seventies. so hazard a guess at 1974?

Metrication was not instantaneous in Australia. It occurred from 1970 to 1977.

Fortunately they’d stopped using Imperial in schools before I went to school.

Peak Warming Man said:

buffy said:

When did we go metric?

Metric money came in in 1966.

No. That was decimal currency.

dv said:

Metrication was not instantaneous in Australia. It occurred from 1970 to 1977.

Fortunately they’d stopped using Imperial in schools before I went to school.

When did magnets go metric?

ChrispenEvan said:

roughbarked said:

ChrispenEvan said:

Good to see you have now done some reading. Nowhere did I say I knew. I look for pages that may explain things. Then I form an opinion. I even say “maybe” etc. If you actually know then why not post that info? Coming in later and saying you know comes across as bullshit on your part. And your “why should i bother explaining things…” etc doesn’t wash. But this is typical of you. The ancients know, shit.

I don’t care how I come across to you. You are a bully and I treat you that way. Always have. If you can prove you aren’t, I’ll change my game.

LOL. You aren’t just posting for me but to try and put up info for everyone who reads this forum. To limit it to me shows you just don’t get it.

Yes Boris. You are doing the same. I’ll say it again. Get a real argument and stop sledging.

dv said:

Metrication was not instantaneous in Australia. It occurred from 1970 to 1977.

Fortunately they’d stopped using Imperial in schools before I went to school.

on 14th February 1966, I was starting High School.

Peak Warming Man said:

dv said:

Metrication was not instantaneous in Australia. It occurred from 1970 to 1977.

Fortunately they’d stopped using Imperial in schools before I went to school.

When did magnets go metric?

When did they need to?

roughbarked said:

ChrispenEvan said:

roughbarked said:

I don’t care how I come across to you. You are a bully and I treat you that way. Always have. If you can prove you aren’t, I’ll change my game.

LOL. You aren’t just posting for me but to try and put up info for everyone who reads this forum. To limit it to me shows you just don’t get it.

Yes Boris. You are doing the same. I’ll say it again. Get a real argument and stop sledging.

LOL, you haven’t added any info this thread that you have actually explained the reason behind. just observations.

roughbarked said:

dv said:

Metrication was not instantaneous in Australia. It occurred from 1970 to 1977.

Fortunately they’d stopped using Imperial in schools before I went to school.

on 14th February 1966, I was starting High School.

I had already started, but only a fortnight or so before.

;)

ChrispenEvan said:

roughbarked said:

ChrispenEvan said:

LOL. You aren’t just posting for me but to try and put up info for everyone who reads this forum. To limit it to me shows you just don’t get it.

Yes Boris. You are doing the same. I’ll say it again. Get a real argument and stop sledging.

LOL, you haven’t added any info this thread that you have actually explained the reason behind. just observations.

I didn’t need to add the info. My walked like a duck question was good enough to answer the OP. You have waffled around looking stuff up ands still haven’t explained it any where near as eloquently enough yet you choose to pretend that I answered with a question rather than info.

You haven’t mentioned hammering the magnet or discussing placing it in a reversed magnetic field.

The easiest way to lose magnetism is to leave it alone for a very very long time. No work involved.

Michael V said:

roughbarked said:

dv said:

Metrication was not instantaneous in Australia. It occurred from 1970 to 1977.

Fortunately they’d stopped using Imperial in schools before I went to school.

on 14th February 1966, I was starting High School.

I had already started, but only a fortnight or so before.

;)

Well I was at a Catholic school so a tad later than you.

roughbarked said:

ChrispenEvan said:

roughbarked said:

Yes Boris. You are doing the same. I’ll say it again. Get a real argument and stop sledging.

LOL, you haven’t added any info this thread that you have actually explained the reason behind. just observations.

I didn’t need to add the info. My walked like a duck question was good enough to answer the OP. You have waffled around looking stuff up ands still haven’t explained it any where near as eloquently enough yet you choose to pretend that I answered with a question rather than info.

You haven’t mentioned hammering the magnet or discussing placing it in a reversed magnetic field.

The easiest way to lose magnetism is to leave it alone for a very very long time. No work involved.

In watchmaking, almost everything has to be demagnetized constantly. We do this with a reversed magnetic field. Magic.

roughbarked said:

roughbarked said:

ChrispenEvan said:

LOL, you haven’t added any info this thread that you have actually explained the reason behind. just observations.

I didn’t need to add the info. My walked like a duck question was good enough to answer the OP. You have waffled around looking stuff up ands still haven’t explained it any where near as eloquently enough yet you choose to pretend that I answered with a question rather than info.

You haven’t mentioned hammering the magnet or discussing placing it in a reversed magnetic field.

The easiest way to lose magnetism is to leave it alone for a very very long time. No work involved.

In watchmaking, almost everything has to be demagnetized constantly. We do this with a reversed magnetic field. Magic.

and as for curie heat. This varies as you may imagine with all ferrous metals. Depending of course as much as anything about the mass of electrons requiring rearranging.

party_pants said:

If I had a horseshoe-shaped magnet and bent it so that the ends touched – would it lose its magnetism?

Eventually but it would not be about your bending effort.

magnetism is about stuff being in alignment, the “domains” being in alignment, if you unbent a horse shoe magnet it becomes a bar magnet, bend it so it touches means that just like the bar magnet and horseshoe the same “domains” are in alignment and the magnetic field just runs internally rather than expanding out into the space around it like a bar magnet or horseshoe magnet.

heat and vibration destroy magnetism as it breaks up the alignment of the “domains”

the magnetic field becomes noticeable when the field leaves the material to expand into space to join with itself