F*cking magnets: how do they work?

Oh god why won’t this meme die?! Every time anyone refers to the infamous lyrics, we end up paying attention to the worst people in the world.

but it dawns on me that the problem here might be that most people don’t know how magnets work. So when we keep making fun of Scrabbly Jay and Mooman 4 Weed (no, i’m not going to look up their names), we’re actually wondering aloud about them. For instance, it topped one of the Lists of things people want famous physicist Sean Carroll to explain.   Recently I’ve even come across a video of Physics King Richard Feynman stumbling over the question.

Dick’s point, in brief, is that asking how magnets work is too difficult a question to answer. It demands a concise description of a completely unfamiliar system in terms of super familiar things. It’s like asking, “how does japan work”. what?

Anyway, i’m throwing my F*cking hat into the F*cking ring, in hopes that we can all forget about Scrabbly J and mooman 4 Weed.

cursing is for louts and people who have just hit themselves on things.

Uhhh. so how much don’t you know about magnets?

Let me premise the explanation:

if you fly a kite, you might see a bunny.

Okay. so if you have never run around with a couple fans as a kid, blowing wind at stuff (and making yourself sound like a dalek), then the explanation will not make any sense to you.

ok. so what’s a magnet? it’s a thing that emits a magnetic field.

every magnet has a north and south pole. magnetic field lines go from the north pole to the south pole. The result of this convention is that the geographic north pole of the earth has a magnetic south pole on it!

okay, so how does a magnetic field work? why does it give magnets their strange properties?

frog.

So a magnetic field goes through and around a magnet the way wind-flow lines move through and around a fan.

We can use this metaphor to explain a LOT of different electromagnetic phenomena, but… lets focus on two MAGNET SPECIFIC phenomena. how Like poles repel each other, and how opposite poles attract.

pushing two fans together is tricky business.

Pretty much, magnetic field lines, like air flow lines, DON’T LIKE GETTING ALL SQUISHED UP. so you held two fans on pivots, and tried to walk them together face-to-face (or butt-to-face), the two fans would rather turn away from each other than kiss. I’d draw this but i’m lazy, and it’s more fun to play with in person.

Okay, so like poles repel. how do we explain opposites attracting?

push the fans together face-to-butt, and then try pulling them apart! it’s hard!

Pushing two fans together face-to-butt causes a kind of suction between the two fans, and they get drawn together. a similar thing happens with magnetic poles, explaining why “opposites attract”.

Okay, so now you know how magnets work. they have a behaviour analagous to a very common system which you are familiar with on hot stuffy afternoons in your living room because you have to practice trumpet instead of going swimming with your sister.

Incidentally, if you really what a magnetic field “is”? Do you remember when i introduced the relativity corrections to how different people at different velocities see things? it turns out that magnetic fields are just the electric fields of electrons that are moving at different speeds to us. the 4-dimensional nature of our universe turns those moving electric fields into magnetic fields! cool!

also, to those of you who want me to say “charges” instead of “electrons”… you’re right, but i figured on not introducing too much information too quickly for explanation sake. also, if you know that, you probably already know how magnetic fields work. so, whatever, dude.

_________________ADDENDUM_______________
Hey, so people want to know about permanent magnets. like. how come a piece of iron is just a piece of iron, but then if you put it in a big magnet it turns into a magnet.

i scribbled some notes. but i had to scan them with my terrible departmental B&W printer. also my nice pens are at home.

aaaannnddd. so how does a piece of iron turn into a permanent magnet?

So yeah, if you can get all of the little magnetic domains in a lump of iron to line up, they’ll stay lined up, and you’ll end up with  a permanent magnet.

sorry the scan sucks.

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13 Responses to F*cking magnets: how do they work?

  1. AmyPNo Gravatar 16 November, 2010 at 12:52 pm #

    This is a masterful explanation, and next time I hear some clown spout this meme I am going to hit them in the HEAD WITH A FAN. TAKE THAT JOSEPH BRUCE AND JOSEPH UTSLER! Phew. Long day.

  2. benNo Gravatar 16 November, 2010 at 1:14 pm #

    WHoa! AmyP knows the true identities of Scabby J and the other guy!

    in other news, i recommend using big heavy iron fans, and not flimsy paper japanese fans when assaulting a clown.

  3. Chuck RNo Gravatar 17 November, 2010 at 2:49 am #

    This explanation is a thing of beauty Ben. Now come up with a great analogy for why some metals are attracted to magnets and some metals are not. I know it has to do with domains lining up but I just love these simple, awesome analogies!

    • benNo Gravatar 17 November, 2010 at 12:12 pm #

      wellllllll…. sometimes the atoms making up a material has no magnetic moment. like, the electrons in it are all spinning in different ways so that there’s no net magnetism to it. In these cases, you can’t induce magnetism.

      Sometimes you can induce a short lived magnetism, like on your fridge door, but the material doesn’t hold a magnetic field very long on its own. in terms of fans, it means that the fans, left to their own devices, swivel around and stop lining up.

      Sometimes you can even get anti-ferromagnetism, where the magnetic field induced by a material is opposite to the magnetic field you apply to it. In other words, it’s like a fridge door that pushes away fridge-magnets, instead of sticking to them.

      a lot of things play into whether/how a material is magnetic, like temperature, crystal lattice structure, the types of atoms involved and even some quantum mechanics.

      I guess what i’m saying is that the broader issues of magnetism and materials is an ocean, and what i fed you in this blog post is a tea-spoons worth of water.

  4. Steve VNo Gravatar 17 November, 2010 at 7:17 am #

    Great explanation! But it only explains one aspect of how they work- could you tackle what makes them work, or why they work? My faint memories of high school science bring back vague explanations of tiny magnets inside the larger magnet, that all need to be aligned, but that always sounded like my grandpa’s explanation of a bunch of little people living inside the radio making the music…

    • benNo Gravatar 17 November, 2010 at 9:59 am #

      there. the addendum has your reply.

  5. PatrickNo Gravatar 17 November, 2010 at 8:33 pm #

    Nice work Ben. Feynman set you up pretty nicely in that video, makes you look smart. Also, like the use of the frog. All hail the Hypnotoad.

    • benNo Gravatar 18 November, 2010 at 2:41 pm #

      yaay

  6. Katherine KobaNo Gravatar 19 November, 2010 at 6:13 am #

    Brilliant explanation! Thank you! <3

  7. MayNo Gravatar 10 January, 2011 at 7:52 pm #

    frog vs. alligator

  8. DevonNo Gravatar 28 January, 2011 at 12:11 am #

    Just started reading your blog, love the explanations (especially the time travel post); you make things make sense. but i found a flaw with your fan analogy… the idea is that like charges repel, which works great when the fans are blowing at one another. but what if you aim the intakes at one another. they would suck themselves together. although i guess in the end it’s just an analogy, but it raises the question, what’s the difference?

    • benNo Gravatar 28 January, 2011 at 9:11 am #

      would they?

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