# Need help with making sphere electromagnet

I am trying to make an electromagnet sphere shape about 6 inches OD. Is this possible?

jambaugh
Gold Member
You can make an electromagnet in the shape of Daffy Duck, take a Daffy Duck shaped piece of iron and wrap wire around it.

Depends. What shape do you want the magnetic field to have?

mfb
Mentor
A spherical symmetry for the field is impossible, but "spherical object with some magnetic field" is no problem.

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This would give me a starting point to construct a spherical magnet of some sort.
Why not take lots of bar magnets and super glue them together in a radial distribution??

You'd need to produce a magnetic monopole to get a field with spherical symmetry.

If you succeed, I'd like to be the first one to invest!

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What would you accept as evidence of spherical symmetry?

The vector field should depend only on the distance to whatever origin you choose.

I have a ball 15cm diameter, wherever I place a compass, outside the ball, the compass points away in a radial (as far as I can tell) direction.
How close am I to meeting your requirement?

I have a ball 15cm diameter, wherever I place a compass, outside the ball, the compass points away in a radial (as far as I can tell) direction.
How close am I to meeting your requirement?

If this is true regardless of how far out I place the compass, then you're describing the field produced by a magnetic monopole.

'impossible' is a strange word to use!!!!

If you take a loudspeaker apart you will find a ring that is magnetised with the poles on the inner surface and the outer surface. This is a cylindrical magnet rather than a shperical magnet.
The same geometry is used in an electric motor.

This would give me a starting point to construct a spherical magnet of some sort.
Why not take lots of bar magnets and super glue them together in a radial distribution??

Your bar magnet idea will result in a non-magnetized sphere because all the fields will cancel out.

Your ring magnet comment is more interesting. If you take a 2 dimensional cross section of the ring magnets field which is parallel to the plane of the magnet but not centered, the field as it is observable within the 2 dimensional cross section will appear to be a monopole.

Now if you can create a magnet in the shape of a 4 dimensional torus you might get a magnetic field that looks like a monopole along a 3 dimensional cross section.

In order to do this you will have to either find a universe with 4 special dimensions or make your magnet small enough to use one of the dimensions that are curled up very small (assuming that they actually exist.

I forgot to mention that I ignored Earth's magnetic field but assumed that would be realised. The effects due to the Earth's magnetic field have nothing to do with the effects of my special ball.

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I forgot to mention that I ignored Earth's magnetic field but assumed that would be realised. The effects due to the Earth's magnetic field have nothing to do with the effects of my special ball.

No worries, my answer assumed the only contribution was from your ball.

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I have a ball 15cm diameter, wherever I place a compass, outside the ball, the compass points away in a radial (as far as I can tell) direction.
How close am I to meeting your requirement?

Your experiment is flawed. It may be that you haven't been thorough in mapping your field or it may be that you compass is flawed.

No worries, my answer assumed the only contribution was from your ball.

Are you ready to invest? Cheques payable to .......

If you can produce that ball of yours (a magnetic monopole) then my god yes, I'll throw all the money I can scrounge up at you.

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Your experiment is flawed. It may be that you haven't been thorough in mapping your field or it may be that you compass is flawed.

You dont know how I did it...how can you criticise it?
The only problem was interference from the Earth's magnetic field !!!! which was easily identified.

If I turn out to be wrong and you win the Nobel Prize and create perpetual motion with your monopole then I will be happy to eat my words, perhaps with a nice onion sauce.

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I do not have these privelidges

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Integral
Staff Emeritus
Gold Member
Why should we spend hours of our time trying teach you mathematical concepts you are not prepared for and will argue with when you can just do it.

I did not ask you to spend hours of your time trying to teach me mathematical concepts!!!
use your hours doing something better !!

I am following an idea that was raised here

Yes you are. The reasons you cannot have what you claim is in the mathematics of Maxwell's equations. If you cannot understand those we must baby talk to you. That has never worked before and never will.

All I can say is keep looking you WILL find an north and south pole.

Please don't waste any more of our time asking us for explanations you cannot understand.

Yes you are. The reasons you cannot have what you claim is in the mathematics of Maxwell's equations. If you cannot understand those we must baby talk to you. That has never worked before and never will.

All I can say is keep looking you WILL find an north and south pole.

Please don't waste any more of our time asking us for explanations you cannot understand.