Electromagnetic induction for "spherical solenoid"

[Mellinia]

Consider the following scenario. If there was a solenoid shaped into a sphere, connected to an ammeter and voltmeter, and there was a spherical magnet inside it,
I have a few questions regarding this:
1) What is the magnetic configuration of most spherical magnets? I.e. are they simply horizontal? Is it possible for the north pole to be on the outside of the sphere and the south pole of the sphere?
2) If I shake the solenoid and the magnet inside it moves, would that produce an induced emf provided that the sphere rolls inside the solenoid?

[Externet]

It is a very good question falling in purely theorethical domain, that had me scratching my head a long time ago, as constructing such spherical winding, would need to be destructed to extract and examine with ferrofluids the spheric steel core to find out if a permanent magnet fas formed.

 

As a guess, it will not become a magnet as the huge number of orientations of the magnetic fields would cancel each other.

 

A soft iron core sphere as in an electromagnet would not show; it would have to be a steel core sphere to retain magnetic properties to be evaluated after extraction from the winding.

 

To check if I understand your concept, would it be like a ball of rubber bands; treating each loop as a single orientation electromagnet, and speculating what would happen if hundreds of loops in all orientations direct their fields to the core ?

The equivalent can be a single wire wound like a ----> http://1.bp.blogspot.com/_AdDvIJr5ZBA/TTCjUeep2cI/AAAAAAAABNw/eOhT7s62ZOQ/s1600/P1060100-2.jpg

And NOT this kind of winding ? ---> http://web.mit.edu/6.013_book/www/chapter8/8.5.html

 

-------> Make one and come back with observations !

Edited March 25, 2013 by Externet

[Mellinia]

Actually, that winding in http://web.mit.edu/6...apter8/8.5.html (the spherical one) was exactly what I had in mind, with the difference that it is not connected to a electric supply, and that there would be more layers oriented into different directions. Was wondering if I could make a generator that did not matter what direction the magnet was moving.
Thanks for that link, btw.

Edited March 28, 2013 by Mellinia

[Externet]

Actually, that winding in http://web.mit.edu/6...apter8/8.5.html (the spherical one) was exactly what I had in mind, with the difference that it is not connected to a electric supply, and that there would be more layers oriented into different directions...

 

Both are spherical, the multiple directions is not the one on the MIT paper; it is the configuration of a yarn ball.

- Not connected ¿?

[Enthalpy]

You can magnetize some spherical material so that its axis points everywhere toward the center - or rather, assemble many magnets on a sphere. But the net result will be zero magnetic field. This is up to now observation; magnetic field flows only as loops, not from or towards a point or region (=the center of your proposed shape).

 

The same holds for coils: you could easily wind several spherical coils around an other, with varied directions, and adjust the currents to obtain a field with sperical symmetry - but this field will be zero.

 

Laws for electromagnetism formulate it as div(B)=0, or "no divergence", or "flux is conserved". Of course, physical laws are here to reflect observation; so many people tried for so long time that more attemps with coils are vain. In a different attempt, some people hoped to observe "magnetic monopoles" particles in colliders, but none has been seen.

 

As for magnets, their poles use to come in pairs, even if shaped as a sphere. At a motor, a magnet can have for instance 6 poles: North at 0, 120°, 240°, and South at 60°, 180°, 300° - even when the magnet is a single part. You can even have poles distributed as NSN, for instance at an E-shaped electromagnet, but because the flux is conserved, the lone South pole must have a bigger area than the two North, or the induction must be stronger there.

[Mellinia]

Both are spherical, the multiple directions is not the one on the MIT paper; it is the configuration of a yarn ball.

- Not connected ¿?

The yarn ball would have a haphazard winding and I was afraid that would not maximize the effect of induction. So I thought maybe I could arrange one coil like the one in the MIT paper, then wrap another one, in another direction, outside the sphere, and repeat again, in different directions, as much as I can. I was thinking about using this to make a electric generator, but putting a spherical magnet inside it.

 

You can magnetize some spherical material so that its axis points everywhere toward the center - or rather, assemble many magnets on a sphere. But the net result will be zero magnetic field. This is up to now observation; magnetic field flows only as loops, not from or towards a point or region (=the center of your proposed shape).

 

The same holds for coils: you could easily wind several spherical coils around an other, with varied directions, and adjust the currents to obtain a field with sperical symmetry - but this field will be zero.

 

Laws for electromagnetism formulate it as div(B)=0, or "no divergence", or "flux is conserved". Of course, physical laws are here to reflect observation; so many people tried for so long time that more attemps with coils are vain. In a different attempt, some people hoped to observe "magnetic monopoles" particles in colliders, but none has been seen.

 

As for magnets, their poles use to come in pairs, even if shaped as a sphere. At a motor, a magnet can have for instance 6 poles: North at 0, 120°, 240°, and South at 60°, 180°, 300° - even when the magnet is a single part. You can even have poles distributed as NSN, for instance at an E-shaped electromagnet, but because the flux is conserved, the lone South pole must have a bigger area than the two North, or the induction must be stronger there.

Arranging infinite bar mangets into a sphere was what I thought, but wouldn't take a huge amount of energy to keep them together since their poles basically repel every other magnet.

Edited March 28, 2013 by Mellinia