hard drive magnets defy physics!

Yesterday, i took apart an old (256 MB) hard drive, and found three VERY interesting magnets. all three are silver in color, so i assume that they are .

Magnet 1) roughly half the size of a grain of rice, this one will lift (well, hold up) 5 grams! it was positioned in the drive so that it stopped the back of the read/write head assembaly from hitting the inner housing.

Magnets 2&3) sort of kidney shaped, about 1 1/4" long, 1/16" thick. these two wer mounted facing each other, with the butt of the read/write assembaly riding between them.

i pryed the two larger magnets off their mounts, and started to play with them. the first thing i noticed, was how increadably strong they are. i have a purple pinch-mark from where they slammed together on my thumb. second, i noticed that, no matter how you situate them, they WILL NOT repel each other.
i labeled each one with a side one and a side two (they don’t seem to have a distinct north/south) this is what i observed:
if you face side one to side one, the magnets slam together, and pinch your thumb HARD.
if you face side one to side two, the magnets slam together, but this time you wern’t expecting it, so they pinch your thumb again.
if you face side two to side two, even though you braced for them to slam together, and pinch your thumb, they don’t. they don’t exert any force on each other whatsoever! no attraction, no repulsion, nothing.

i can’t figure out for the life of me how this can be posible. don’t ALL magnets have both attractive and repulsive forces? don’t ALL magnets have a north and south side? (which one is the “bad” side of the magnet?)

eggo

Hmmmmm…

I have noticed the incredible strength of HDD magnets, But I hadn’t done any of this type of experiments. Tomorrow, since I have a likely-dead hard drive in my cube, I’ll do a little “research.” If I get time, that is. Hopefully, tomorrow won’t be a repeat of today.


A committee is a lifeform with six or more legs and no brain.

that first paragraph should read:

Yesterday, i took apart an old (256 MB) hard drive, and found three VERY interesting magnets. all three are silver in color, so i assume that they are Neodymium-Iron-Boron magnets.

eggo

eggo wrote:

Here’s my off-the-cuff hypothesis: Probably the magnetic charge does not extend through the entire bodies of the objects you are describing. Even though the magnetism seems suprisingly powerful, recall that the strength of the magnetism drops off quickly. Try getting one of the magnets to stick to the side of the refridgerator through a peice of paper, then through two pieces, and so on until it won’t stick anymore. And I’ll bet the distance between end of the actual magnetized material and the unmagnetized back of that widget is a lot more than the thickness of the paper that the magnet couldn’t get through.

nope, they are epoxied to aluminum mounting brackets, but the brackets are only 1/16" thick, the magnets will stick through my hand (and still exert a painful amount of pressure)

eggo

i wanted to verify that it wasn’t just somthing about my hand, so i stuck it to the fridge through my copy of “a brief history of time” (198 pages, hardcover) and 'ol Stephen Hawking is still sitting on my fridge with that weird look on his face.

eggo

Well, that theory’s shot. My next theory is that it has something to do with invisible elves.

yeah, i was thinking the same thing. or maybe the ether…

eggo

It’s actually hard to hold two small magnets and make them repel. They will try to twist in your hand until they are aligned correctly to attract each other. Also, magnets always have both poles, but the orientation can be anything; if it is disk-shaped, the two poles can correspond to the two sides, or two edges of the disk.

You’ve all got it wrong… First off, you were never meant to open your HD. Why did you do that? <sigh> Second, don’t go pfutzing around with things you know nothing about. It’ll get you into nothin’ but trouble. Remember that “incident” at Roswell? There’s your answer… that there is alien technology.

Speaking of trouble, I’d like to warn you that everyone involved in this post is in grave danger. Pack only what you need, and leave… NOW!

This is The Key.
Most magnets have the thin sides polarized. These have the Big Flat Sides polarized. Odd, but still cool. BTW- the magnets are brittle, and will break into bits if jarred enough, and the gold coating is razor sharp enough to slice well when peeled off. Otherwise, have fun with them! Go into a TV section of Sears, and… put them somewhere near a TV. It will drive the repair people nuts! (Just Joking- but if you do this, turn off the TV for 1/2 hour and it -should- degauss)


I have no digital watch

Here is fun experiment to try: Get a soda straw, the longest you can find. Fill it with water and clamp the ends. Stick it in the freezer and freeze it solid. Take it out and suspend it from the ceiling with a piece of string at the middle. The straw should be more or less parallel to the floor and able to swing freely. Now see how the ice reacts to your magnet. Note that this requires a very strong magnet.

i hope you’re joking.
does it have to be a straight-sided straw? i tried it with one of those long, ribbed straws once (the ones you get in a “Big Gulp”), and nothing happened. (i didn’t have these magnet then, but we used a tesla coil.

eggo

i hope you’re joking.

does it have to be a straight-sided straw? i tried it with one of those long, ribbed straws once (the ones you get in a “Big Gulp”), and nothing happened. (i didn’t have these magnet then, but we used a tesla coil.

eggo

The magnets may be horse-shoe shaped inside, so that both north and south poles are on the same side of the magnet (the sides which attract most strongly). If you have the sides which attract the strongest together, and rotate one 180 about the line connecting the centers, they should then repel. It’s probably real hard to hold them this way, since they’ll want to twist.


It is too clear, and so it is hard to see.

yes. you are absolutly right! if you twist them around, they repel each other – vigorously. thanks Zen.


eggo

My Web Page:SMITE WARNING it may offend you.

did anyone even notice my little “bad side of the magnet” joke at the end of the OP? i thought that was damn funny.


eggo

My Web Page:SMITE WARNING it may offend you.

Eggo,

quote (originally from me - referenced by you):

You’ve all got it wrong… First off, you were never meant to open your HD. Why did you do that? <sigh> Second, don’t go pfutzing around with things you know nothing about. It’ll get you into nothin’ but trouble.

Quote from you:

i hope you’re joking.

In no way was I joking. That’s serious stuff man… and THEY will be comming for you soon. You do have your bag packed by now right?

BTW…

Yes, I was joking.

Eggo, didn’t catch it at first, but now I do.
funny