Magnetic Levitation Idea, tell me why this won't work

[markvaughn]

Hello all! new here, first post, nice to meet ya. I've just had this idea in my head for a long time, and i've been wanting to make a real life model of it but i'm not entirely convinced that it'll even work, please help me to see whats wrong with this idea..i don't know how to post pics but i'll put links to them.
If you took a wooden sphere and drilled 1/4" deep holes with a spade bit all over the surface, each hole with a diameter the same diameter of the magnets to be used. And then superglued a magnet set into the hole one at a time in each hole, with the positive pole facing out.(or negative, but we'll just go with the positive for this) Assuming that the magnets were spaced out evenly over the whole sphere, and set 1/4" (or more if need be) deep into the wood, would you have a sphere that was completely surrounded with a positive magnetic force field? Bear with me... if that worked then couldn't you make a wooden rectangular box for a base and set magnets in it the same way as with the ball with the positive poles facing out and equally spaced, set into the wood and superglued down. when you placed the ball over the base, would the ball be able to "land"? i know it would probably try to jump off the base but then you could just build a fence to keep it from falling off the base. Assuming (and i'm sure i've already made an ass of myself) that this all worked, wouldn't you have a ball levitating over a base and perpetually spinning trying to either land or escape. i'm sure that i'm missing some basic mundane point here, or its already been done, so just go ahead and tell me where i messed up.. here are some crude drawings to help you see what i'm talking about if i was unclear, thanks for reading this and helping! Mark

http://www.geocities.com/markvaughn99/sphere.JPG

http://www.geocities.com/markvaughn99/base.JPG

http://www.geocities.com/markvaughn99/fence.JPG

http://www.geocities.com/markvaughn99/levitate.JPG

 

[prex]

Well, why not, but what's this for?
There's nothing special in having magnets repel themselves, keeping objects from going into contact.
Also note that your ball will likely go towards a corner of the rectangular area and stay there, but this could depend on the detailed layout of the magnets.

prex

http://www.xcalcs.com

Online tools for structural design

 

[markvaughn]

is there anything like this already made? and if you made the base of magnets concaved so it was slightly shaped like a bowl, would the ball gravitate towards the middle? and just float there? or is this breaking earshaw's laws? So prex, i'm just confused, you are saying that this would probably work but whats the big deal? what if you made this on a larger scale and made the base a mile long like a pathway and made it so you could transport something inside the ball. what friction would there be? just air right? and if you put this mile long base and ball in a vacuum there would be no air friction (resistance) then what friction would there be? possibly none? i know thats not right, i just think there would be a lot of possibilities with this if it actually worked.

 

[aspearin1]

The idea is old but not completely grasped. Hoverboards, like in Back to the Future II, actually do exist. Or did... but it's not easy to stear or balance a top heavy skateboarder on a completely frictionless plane. In addition, the power necessary to keep people moving would create such an EMF that people would get brain tumors and pacemakers would stop.

http://www.o-keating.com/hsr/maglev.htm

ChemE, M.E. EIT
"The only constant in life is change." -Bruce Lee

 

[MagMike]

Hello markvaughn,

While you do have a clever idea, you're basically describing the prinicple behind maglev trains. Of course, maglev trains use an electromagnet repelling against a permanent magnet, but the idea is the same. The key thing is that the repelling magnet (in a maglev situation) is restrained from flipping over during repulsion.

One thing to keep in mind regarding your description of the magnetic field distribution around your sphere: No matter how evenly spaced the magnets are around the sphere, you will have an uneven distribution of magnetic field. It will be mostly positive (or negative, depending on whether you had all North or all South exposed), but there will be uneven fields between the magnets. That gradient will significantly reduce the repulsion force.

One other thing, for your base: You'd be better off just having one large rectangular magnet instead of an array of disc magnets. A bowl shaped base magnet will not help very much. As you mentioned, Earnshaw's theorem makes a compelling argument as to why two permanent magnets won't levitate stably unless one degree of motion is constrained.

There are novelty devices that exploit this phenomenon. I've seen pen holders and a top that use this effect. Last spring, I helped a schoolkid design a working model of a maglev train for a class project (he did the hard work, I just supplied the materials). It was quite a challenge to keep the train on the track.

 

[RHMagster]

Hello markvaughn,

I hope this will help,

MAgnetic levitation, a long sought after dream when it comes to stability. There are some experimenters out there that have found - when building a levitation device - suspending one magnet above a magnetic base - by spinnig the magnetic base you acheive a form of stability. You may try this in your attempts.

Also, another possibility, try Diamagnetic Levitation. Unlike Ferromagnetism and paramagnetism, this is considerably more stable.

Consider the maglev train except using eddy current.
A magnetic field moving across say copper or aluminum producing eddy currents into the material. The eddy currents repel the field developed in the magnet (at sufficient speed). They are in fact opposing polarity to that which created them.

Just some ideas that may help.

You can find more on Diamagnetic Levitation at

http://www.quad-tech.com

RHmagster

 

[markvaughn]

Hey guys thanks for all the responses. MagMike, you said "No matter how evenly spaced the magnets are around the sphere, you will have an uneven distribution of magnetic field. It will be mostly positive (or negative, depending on whether you had all North or all South exposed), but there will be uneven fields between the magnets. That gradient will significantly reduce the repulsion force." I guess i just need to build this thing, to see for myself, because the repulsion that the magnets i have is very strong, strong enough to lift itself and plenty of extra weight, i'm still somewhat convinced that even with the force weakened, it would be stronger than the effects of gravity. i know this is a very simple idea, i just wonder if its been thoroughly explored. It seems to me that the small amount of attraction that it may feel from the sides of the magnets (maybe) or from the gaps in between the magnets wouldn't be greater than the repulsion of the very strong rare earth magnets. it seems that the ball would just spin and bounce all over the place trying to settle down. and about the fence around the base, it could have magnets embedded in it as well, repelling side facing in, to keep the ball from just trying to rest in a corner. i appreciate the help, i'm not very smart in this subject really, not at all actually, its just an idea i'm playing with, probably a very old and basic idea, but its fun to me.