How do magnets work?

  • Thread starter Jarfi
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  • #1
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I know a little bit about them already but I don't know exactly just how and why they work.
I know that they are caused by movement of electrons/electric charges.
I know that when all electrons spin in the same direction we get magnetism, and that in a current of electrons we get magnetism.
But I don't understand why do magnets only attract metals and not for example wood.
And why do spinning electrons create a force that draws or pushes them to or apart from each other?
I think it has something to do with the whole charge being 0 and that when the - charges move they move other - charges with them but I am pretty confused and this is just what i assume.

can someone please explain why magnets pull metals and other magnets to each other?
 

Answers and Replies

  • #2
Drakkith
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I can't answer everything, but I can explain why magnets attract certain materials and not others. Basically it comes down to the material having the ability for its parts, (molecules, atoms, and bigger pieces of itself) to align themselves to a magnetic field or to already be aligned. When they arent aligned a magnetic field exerts equal attract and repulsion forces to the object as a whole, resulting in no net force. Certain metals have the ability to align with the magnetic field when it is applied. Its atoms and such will align so that their south poles of their own little magnetic fields will be towards the north pole of the magnet and vice versa. This is also the reason that you can stick a magnet on a piece of metal, and have the metal itself become magnetically attractive to other things on its other end. Its a bit more complicated, so I recomment hitting wikipedia up on this or getting a book on it.
 
  • #3
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I’m not going to provide a link, Jarfi, because it is actually quite easy to find, but there is a famous clip, available to watch on YouTube, of Richard Feynman being asked this very question. The clip is famous because Feynman goes off on a tangent pondering the problem of how and why questions always leading to another how or why until the inevitability of crashing up against an ‘I don’t know’. I have seen people on this very forum misinterpret this as evidence that Feynman himself didn’t know the answer. Of course Feynman knew the answer as well as anybody does, and lost in the middle of his digression he does actually supply it. But the central point that Feynman makes is that the behaviour of magnets is a manifestation of exactly the same basic phenomenon that means that you cannot pass your hand through the desk on which the computer you are reading this on is sat – what we call the electromagnetic force. But the behaviour of magnets is mysterious enough to you to make you ask ‘why?’ yet it never occurs to you to ask ‘why can’t I pass my hand through the desk?’ As Drakkith has said, the behaviour of magnets is to do with the fact that all the directions of the electromagnetic force of all the electrons in the atoms making up the magnet are aligned , giving a cumulative effect akin to the cumulative effect of a crowd at a football match all chanting the same thing. Whereas, in your piece of wood they are all in random directions, all cancelling each other out, like the background hubbub if everyone in that football crowd is just holding their own individual conversation. And when your hand meets the desk, the negative charge of all the electrons in the atoms making up your hand, repel the negatively charged electrons in the atoms making up the desk.
 
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  • #4
Meir Achuz
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"I know that they are caused by movement of electrons/electric charges."
The main source of ferromagnetism is NOT the movement of electrons/electric charges.", but the alignment of the spins and intrinsic magnetic moments of bound electrons.
 
  • #5
jtbell
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In classical electromagnetism, we often model the magnetization of a material by invoking fictitious "bound currents" on the surface of the object or inside it, but these do not represent an actual flow of electrons.
 

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