Is there such thing as a ball magnet?

[ironizer]

I'm trying to find a magnet that is a spherical shape and has one pole on the outside surface and the other pole on the core. If anyone has found something like this please provide link.

[NeonBlack]

I believe that such a thing can not exist.

[Klaynos]

Yeah, I don't think you can do that, because the field lines need to be closed loops...

[ironizer]

even if the ball was hollow?

 

What if you make sections of it and forcedly assembled them together. Would that work?

[Klaynos]

Not even if it was hollow.

 

If you made sections and forced them together I dunno what would happen, you'd probably get significant pole switching around the boundries of each magnet...

[YT2095]

do a simple thought experiment here and break it down into discrete parts.

imagine a load of Wedge shaped magnets, like a slice of pie each.

the small end is North for instance and the outer edge is South.

 

now try and fit them all together to form a complete pie again, you`ll see that they will repel, all the Norths in the middle and the Souths around the edge together.

like and like repel, it would fly apart, and even if you Did find a way to hold it together with Glue or something, it would slowly destroy the all the magnets.

 

so nope, it`s Not going to happen

[DrDNA]

Hmm.

What would happen then if you took an object like a small balloon (I say like a balloon, because a regular latex balloon probably would not survive the process and it should be small to fit the tool below) and coated it with a rare earth magnet material like neodymium iron borohydride? You can pretty coat (like spray painting almost) things with this stuff in, for example, an ion beam coater or a sputter coater. I've successfully coated very small flat surfaces with Nd- Fe-Borohydride in this manner many times in order to make them magnetic .

[John Cuthber]

You might have more success with a boride rather than a borohydride.

 

The idea of a bunch of wedge shaped magnets making a monople isn't new.The idea was raised in the Daedalus column of New Scientist Sept 10 1970. It was (so I gather) analysed by Dr Epsilon and Mr J Middlehurst in Wireless world Dec1978 p 67 and Sept 1979 p82.

The analysis is described as unsympathetic.

[DrDNA]

You might have more success with a boride rather than a borohydride.

 

 

Correct. It is boride. Sorry for the confusion.

I have organometallic reagents on the brain....eg, sodium borohydride, sodium cyanoborohydride, etc

 

Do you know of a link to the info in that paper (or similar)? Their archive seems to only go back to '89.

[ironizer]

The idea of a bunch of wedge shaped magnets making a monople isn't new.The idea was raised in the Daedalus column of New Scientist Sept 10 1970. It was (so I gather) analysed by Dr Epsilon and Mr J Middlehurst in Wireless world Dec1978 p 67 and Sept 1979 p82.

The analysis is described as unsympathetic.

 

1970s? I figured someone thought of this centuries ago.

[Sisyphus]

I think Klaynos is right. You simply couldn't get that alignment, because the need for closed loops would force pole switching all over the place. The overall effect would be non-magnetic.

[DrDNA]

Impossible I say.

But it looks like you can just buy them...........

 

http://www.engconcepts.net/List_Of_Sphere_Magnets.asp

 

http://www.dansdata.com/magnets2.htm

[Klaynos]

I don't think they have a single pole on the outside though.

[DrDNA]

You are apparently correct Klay.

 

The biggest Nd magnet sphere you'll find.

1-1/2" Dia NdFeB Sphere Magnet, Grade N45, Ni-Cu-Ni Plated with Mirror finish, Magnetized through the Poles (like the planet Earth). Click on image for larger pic.

WARNING - VERY POWERFUL

( just try and pull 2 of these apart! )

1-1/2" Sphere

Pack of 1: $48.00

[ydoaPs]

You are apparently correct Klay.

 

The biggest Nd magnet sphere you'll find.

1-1/2" Dia NdFeB Sphere Magnet, Grade N45, Ni-Cu-Ni Plated with Mirror finish, Magnetized through the Poles (like the planet Earth). Click on image for larger pic.

WARNING - VERY POWERFUL

( just try and pull 2 of these apart! )

1-1/2" Sphere

Pack of 1: $48.00

 

Not the biggest. You can buy 2" NIB spheres at unitednuclear(Supermagnet #200).

[ironizer]

These things would be the coolest toys ever. I want some but 30 bucks is too much. I got .25" cubes for 15 cents each (a while ago). They are grade 40 i think.

[DrDNA]

These things would be the coolest toys ever. I want some but 30 bucks is too much. I got .25" cubes for 15 cents each (a while ago). They are grade 40 i think.

 

The smaller ones are much cheaper I think.