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MarkerMage World Ends Oct 21, 2011 from My own little world Since: Aug, 2009
World Ends Oct 21, 2011
#1: Apr 16th 2011 at 10:34:54 AM

OK, so I have a few questions about what magnetism will do and I don't have big enough magnets to find the answers through testing.

The Situation
I want to make a fantasy world where the force that keeps people's feet on the ground is more like magnetism than gravity. It started as an explanation for upside-down Floating Continents, but I want to know how it would affect other things. Seeing ferrofluid in action has convinced me that I really don't know enough about magnetism, so I thought I would ask some questions here.

1. If you have a cylindrical magnet with the poles on the flat ends, would the ferrous objects on one of those flat ends try to move to the center of that side, the edges of that side, not care, or some answer I haven't thought of?

2. If the cylindrical magnet has a hole that goes through the center of the pole ends, would that change anything?

3. If one of the pole ends was bumpy instead of flat, would ferrous objects be pulled to the top of the bumps, to the area around the bumps, stay away from the bumps, or be unaffected by the bumps?

4. I've seen numerous videos where ferrofluid forms spikes when it's being pulled towards a magnet. I want to know how an increase or decrease in the magnet's surface area would affect those spikes that it forms.

5. What if the amount of ferrofluid was increased or decreased instead?

6. What if the strength of the magnetic field increased or decreased instead?

7. If you had dunked a cylindrical magnet (poles at the flat ends) into ferrofluid in zero gravity, what would it look like? Would the ferrofluid coat the entire magnet and form spikes at the two ends? Would the ferrofluid form spikes all over the magnet? Would the ferrofluid gather around the two poles and leave a ring around the middle of the magnet bare, creating what looks like a spiky dumbell?

8. How would the ferrofluid on the magnet in the previous question be affected by a second magnet being put near it? Would the ferrofluid spikes try to bridge the gap between the opposite poles of the two magnets? Would the ferrofluid spikes sink down into a pool if the magnets' alike poles are facing one another?

9. Do any of you know of any videos that would show me the answer to any of the above questions instead of merely telling me?

10. And since it would be weird to stop at 9 without going on to 10, is there any particular reason for "magnet" and "magic" starting with the same three letters? Like the two words having shared a lot more meaning in the past?

Thank you.

Thinking of ideas to use with a literary work that is meant to be WikiWalked through.
Yej (4 Score & 7 Years Ago) Relationship Status: They can't hide forever. We've got satellites.
#2: Apr 16th 2011 at 11:31:55 AM

As a general reminder, I would like to point out that high-strength magnetism is not a toy. grin

1. The center, AFAIK.
2. Yes, a lot. However, the result is quite complex, and you'll have to ask someone more educated than I.
3. I think the objects will attempt to be as low down as possible.
4. The spikes would probably be thicker.
5. No difference, other than longer spikes.
6. Er... Dunno.
7. You'd get a visualisation of magnetic field lines. Sort of like this, except in 3D.
8. That's three questions! tongue In general, the ferrofluid will follow the combined magnetic field lines, and these lines will warp depending on the positions of the magnets. If you have and/or can borrow the equipment, try setting up a few bar magnets under a piece of paper, and then putting iron filings on top of the paper.
9. No, sorry.
10. No. At least, according to Wikipedia, although they both derive from Greek, they're from different roots.

However, if you're using this as a justification for a Floating Continent, do not be dissuaded by magnetism not doing what you need. James Cameron ran into the exact same problem, didn't even handwave it, and the worst that happened was some engineers shouted at him. (Specifically, they shouted at him because the magnetic field supporting the flying mountains turns out to be planet-shattering.)

edited 16th Apr '11 11:34:00 AM by Yej

MarkerMage World Ends Oct 21, 2011 from My own little world Since: Aug, 2009
World Ends Oct 21, 2011
#3: Apr 16th 2011 at 12:34:44 PM

Thank you.

I've read enough warnings about rare earth magnets to get the idea that I shouldn't play with them until I've gotten a relevant physics degree and a medical team nearby in case of emergency.

I'm not going to be dissuaded by magnetism not doing what I need. I'm mostly asking so I can do some Show, Don't Tell in regards to the floating continents. I want to create a text-based adventure game that involves human scientists that are familiar with the physical laws of our universe exploring the fantasy world I'm world building and trying to come up with theories about how their new home works. So I want to be able to give the player a good number of clues that the Floating Continents rely upon a magnetism-like force to float and picking up a piece of the ground and turning it upside-down will cause it to float too. I want to have players see what they think to be impossible and think about what allowed it to be possible, because that's what the characters they'll be controlling are trying to do.

Thinking of ideas to use with a literary work that is meant to be WikiWalked through.
Yej (4 Score & 7 Years Ago) Relationship Status: They can't hide forever. We've got satellites.
#4: Apr 16th 2011 at 12:46:49 PM

Rare earth magnets are fine, since they generally don't put out any more energy than your average speaker cone. What I mean by "high-strength" magnetism is basically anything capable of supporting anything more than 20 metres or so in the air. Magnetic force drops off incredibly fast with increasing distance, so any magnetically-supported thing floating more than 80ft or so is scientifically unfeasible. (Unless you're on a magnetar. If you're not, then you will be shortly.)

edited 16th Apr '11 12:47:53 PM by Yej

MarkerMage World Ends Oct 21, 2011 from My own little world Since: Aug, 2009
World Ends Oct 21, 2011
#5: Apr 16th 2011 at 1:23:41 PM

Is that "20 metres or so in the air" thing just for cases where the magnetic levitation is opposed by an acceleration of 9.81 metres/second^2 towards the ground, or do I have even more to learn about magnets?

Thinking of ideas to use with a literary work that is meant to be WikiWalked through.
Yej (4 Score & 7 Years Ago) Relationship Status: They can't hide forever. We've got satellites.
#6: Apr 16th 2011 at 1:27:00 PM

Yes. If the magnetic force at 20m can cancel out the weight (=9.8*mass) of a 10+kg object, IMO, something's wrong.

edited 16th Apr '11 1:27:20 PM by Yej

storyyeller More like giant cherries from Appleloosa Since: Jan, 2001 Relationship Status: RelationshipOutOfBoundsException: 1
More like giant cherries
#7: Apr 16th 2011 at 5:51:06 PM

Generally, you can't get permanent magnets anywhere close to that strong though. You need serious electromagnets for that. Which would probably involve superconductors and a liquid helium cooling system to prevent energy losses from being too high, but then you run into issues with critical fields and the like.

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Yej (4 Score & 7 Years Ago) Relationship Status: They can't hide forever. We've got satellites.
#8: Apr 17th 2011 at 8:48:55 AM

I don't think you can get non-Phlebotinum solid magnets that strong, at all. They only appear in really odd places, like the cores of planets.

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