Anonymous
Anonymous asked in Science & MathematicsEngineering · 1 decade ago

# Magnets: How do they work?

don't lie or ill get pissed!

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• Anonymous

Pure mother**cking magic.

• 1 decade ago

The last answer is about 50/50. We do understand why the electrons align very clearly, which I'll explain some. We have a pretty good understanding of why we only see dipoles, too, which I'll mention at the end but not explain. This is going to be long but will explain a lot.

First: I'm talking about ferromagnets, which is what we mean by permanent magnets.

Electron spins/dipole moments are oriented randomly in a block of material. Most "nonmagnetic" materials have paired valence electrons - these are the paramagnetic and diamagnetic media. They don't have a strong magnetic response because the electrons tend to all cancel each other out.

Some materials have unpaired valence electrons but are oriented randomly still - it's not a magnet. But if you apply a magnetic field to it, it becomes like a really strong magnet, which goes away when the field you applied goes away. These are the ferrimagnetic and antiferrimagnetic media.

Others have unpaired valence electrons but are NOT oriented randomly on a LOCAL scale. This is totally a quantum effect. This means, on a local scale, there is a net magnetization. However, the quantum effect is weak at larger distances, so there are blocks inside the material that are magnets, but they aren't aligned with each other. They're random, so again, no magnetization. If you apply a magnetic field, again the blocks align so they become really strong magnets. However, if you take the magnetic field off, the blocks do NOT go back to being randomly oriented - they stay aligned. This is how we have permanent magnets, and these are the ferromagnetic materials.

If you think about the 2nd-last sentence I wrote above, this is where the hysteresis the other guy mentioned comes in. If you could create a block of ferromagnetic material from raw protons/neutrons/electrons, it would not be a magnet, because those "magnet blocks" are randomly oriented and tend to cancel each other out. You need to apply a magnetic field to make it a permanent magnet, and the stronger the field you apply, the stronger the magnet is. In other words, the strength of the magnet depends on what happened to it in the past - hysteresis. Another interesting effect of this is that permanent magnets aren't really permanent - they lose their strength over time. It's a long time, so we don't notice it every day, but it has been used by geologists to look at, for example, how the Earth's magnetic field changes.

There are also electromagnets - by Maxwell's equations, if you have a loop of current it produces a magnetic field. This is why wires wrapped around a nail give you an electromagnet.

About magnetic monopoles - there has been theory going back 70+ years about them. See references for further reading if you're real technical. We believe that monopoles actually do exist in nature, the problem is finding them. Leaving out decades of theory work and simplifying considerably, the LHC at CERN can detect particles in the range of the TeV (10^12 eV). Theory shows that magnetic monopoles should be in the range of 10^16 GeV (10^25 eV). They're so large/energetic and the forces between them are so strong that the only way we can think of finding them is with cosmic sources and looking for effective monopoles - we won't be able to separate/create them with a particle accelerator. There have been recent papers discussing the EFFECTIVE monopoles, though. See references.

I doubt anyone's still reading after the insane thing about tornadoes or whatever the hell it was, but if you are, hopefully this was helpful.

It has come to my attention that this may be a stupid troll post. In which case, **** you.

Source(s): Dirac wrote two papers in the 30s and 40s about monopoles t' Hooft and someone else (Russian) had great theory papers about monopoles in the 70s Two recent papers in Science talked about effective monopoles, both late last year, in spin ices, strange materials made with rare-earth elements.
• 1 decade ago

Well the past answer is not entirely true.

EVERY SINGLE ELECTRON in the known universe is a small magnet itself.

in a normal molecule all electrons in the atoms are orbiting their nucleus randomly.. each one of them in different directions. Without alignment, forces act separately and little or no magnetic properties are observed.

In magnets 99% of the electrons are spinning in the same direction. What we know as the "magnetic field" is created by the effect of all the electrons in a compound spinning in the same direction around its nucelus. It is the same thing that happens when you run electrons (electric charge) over a copper coil... it generates a magnetic field.. most of the time polarized.

Every compound that produces a magnetic field, either from electricity pass or by natural electron alignment is a DI POLE.. meaning it has a north pole and a south pole (positive and negative) and they repel each other.

NOBODY understands clearly why the dipole condition is allways present, and some even state that theoretically it is possible to create a MONO POLE, meaning a "positive only" or "negative only" magnet. But this is still early science.

Another BEAUTIFUL property found in nature is HYSTERESIS, which is the abbility of a compound to hold a specific condition for a period of time without changing its composition... that is why you can "magnetize" metals and they will hold the magnetic condition.... for example.. your hard drive... which is composed by this type of materials. We use this to store information.

Following what i have explained about the electrons... when you approach a magnet to a metal, all the electrons in the metal will be aligned to the same direction, and will replicate the field untill they go back to their original random spinning state.

There is a lot to research about magnets yet...

Hope it hepls

Pedro

PS: About the tornado theory relating to magnetism.. i have never heard anything more ridiculous in my life. Roofs fly because the wind mass has a lot of kinetic energy which creates forces and vectors strong enough to lift the roof's weight.

On the other hand .... there is no such thing as a "magetic vacum".... magnetism is the same on vacum or without it...otherwise electric motors would not work in space.. right?.. the biggest motor known in earth is EARTH itself.. the metalic nucleus of the planet spins.. and that's why we have a magnetic north and a magnetic south.