Toy with magnetic levitation

[quark]

Gentlemen!

Recently I saw a toy (may be it is new to me) of this shape <>=<> but with rounded edges.Below that there is a U shaped base (with less deep groove) and a glass is attached to that base. When you see from the front view the above shape seems to be cantilevered on the glass, but it is absolutely floating in the air. When you spin the shape it rotates without falling down and without sliding.

Whenever I try to keep magnets one on top of another, the top one is always thrown away. But here it stands.

I jus want to know the working principle and the equations. any ideas?

Thanks in advance

 

[tonymac]

Hey,
They could be using two magnetic fields, and trapping the object in betwwen them. That would keep the object from being tossed aside and would keep it in the air.
Where did you see this?

 

[DanDel]

I've seen something similar. There are usually weights which keep the floating magnet from flipping over but are not heavy enough to push the floating magnet down enough to touch the stationary magnet.

 

[peebee]

The bowl shape will help too.

When you try to stack magnets, it's kind of like trying to balance a ball on top of a hill, it wants to roll down one side or the other.

But with the bowl shape, if the magnets are all arranged properly then, well, it's more like setting a ball in a bowl rather than on a hill. It wants to stay there.

Add the weighting that DanDel's talking about and you're all set.

 

[quark]

I found this toy in a gift articles shop and is made in China. The main thing blocking my idea is its sheer simplicity. (the toy costs less than 4 USD when converted from my monetary units)

I also posted this in Mechanical Engineering forum and these are the ideas given by the tipsters.

1. The glass sheet stops the magnet from having axial movement and if I reverse the direction of the above shape it sits on the base. (anyhow I have to check this)

2. I feel the circular shape is given to keep CG of the toy in its base always.

But if we have to repel the body from its base, the body and the base should form two opposite polls. Now, how is it possible to maintain a cylindrical (or spherical) body at one pole only? One expert said that by using sheet magnets this is done (brilliant idea). But keeping the cost in view I don't think that is the case. Secondly, I feel for cylindrical and spherical magnets Declination and Inclination effects don't matter.

Note: 1. This toy is witout any weights. I think that model is a second variant.(I feel for cylindrical and spherical magnets Declination and Inclination effects don't matter. So no need of adding weight for this particular model)

I appreciate your further inputs.

Best regards,

 

[peebee]

Quark, why don't you post a link to your other thread on this subject. Just type in the thread number from the top of the page, like this: thread237-56057 (don't bother clicking this one, it's just a circular link to this very page), eng-tips will automatically convert it to a blue underlined hypertext link.

 

[quark]

thread404-56058

 

[gordonl]

A shot in the dark:

I wonder if the shape of the floating object is the key. Perhaps the magnet itself is arranged in the thicker border, with some permeable material in the center. This may cause the majority of the flux to pass through the donut hole versus the outside edge of the object. This may substantialy increase the stability of the object from flipping.

Just speculating, because it's fun.

 

[jbartos]

Suggestion: The toy has to be considered to be a system. This system is at equilibrium point, which is possible to calculate, design or fine-tune. Similarly, consider a ball on the tip of a pencil. It is possible to fine tune that it stay there, which means that an equilibrium point has been reached.