Why are magnetic things magnetic?



Why are magnetic things magnetic?

In: Physics

[Even award-winning physicists struggle with this](https://www.youtube.com/watch?v=MO0r930Sn_8) and that link is probably the best explanation I can think to give at an ELI5 level. Ultimately it has to do with things that you need some basis in physics to really get into at any depth that doesn’t beg the question – is that certain materials have a property that causes their electrons to all move in the same direction (namely that their outermost shell of electrons is not full) and that causes other materials with that same property to interact with it in weird ways involving the electromagnetic force.

I’m going to assume you’re referring to solid state magnets, like the ones in a compass, and not electromagnets, which are a little different (but not as much as you think!)

Also this is a really cool topic, but to actually get to the meat of it it’s kinda impossible to ELI5, so I’ll give a simplified explanation and I’ll try to ELI5 at the end.

Electrons, the things that cause chemical bonding as well as causing your lights to go on and your car to start, have a magnetic dipole moment. What this means is that they themselves are essentially tiny little magnets. When in an atomic or molecular structure, electrons like to fall into a very ordered structure of things called orbitals, which you can think of as containers for electrons. Weird thing about these orbitals though, is that they only have enough room for exactly 2 electrons, and even weirder still, for two electrons to occupy the same “container”, their magnetic moments must be opposite each other, which means that the magnetic field produced by these two electrons is 0.

Orbitals themselves are organized into levels of energy, think of them being on shelves on a wall, and as the shelves get higher, they can have more orbitals on them, but when filling these orbitals up with electrons, it’s always easiest to reach the lowest shelf first, right?

Enter weird orbital property number 3, it’s always just ever so slightly harder to put the second electron into an orbital that already contains one electron! So this means that you put one single electron in each of the orbitals on a whole shelf before putting any second electrons into an orbital on that shelf. What this means is that for specific arrangements of electrons, there are several unpaired electrons, and since each of these electrons is like a tiny magnet, there is a magnetic field generated.

This gives way to a phenomena known as paramagnetism, which is when you take a material and place a magnet near it, that material actually becomes magnetic in the opposite direction, because all of those individual unpaired electrons suddenly align with the magnetic field, like how when you place a magnet close to another magnet it flips around!

Some materials will maintain this alignment after the external magnet is removed, and this is where most magnets come from.

Ferromagnetism is when this process occurs spontaneously in the material, without the application of an external magnetic field.

Legitimate ELI5: magnets work because inside of them, there are lots and lots of tiny magnets. Most of these magnets are snapped to another magnet, however, some of them are by themselves! When a magnet is passed over this material, all those millions and billions of tiny magnets suddenly snap to face the big magnet, and all those tiny magnets all add up to one big magnet!