Generating a spherical EM field

Well, choose a spherical container made of iron or mu-metal. Because otherwise magnetic fields propagate to infinity If you want uniformity, that is an additional impossibility.

Is there such a thing as a spherical magnetic field? Where would all the vectors point?

John

You can get a quite uniform magnetic field in a volume located well inside a cube with a pair of Helmholtz coils on opposite faces. Maybe a 3m cube for a 1m cube volume.

Not sure about spherical, maybe you'd need to crack open your jar of magnetic monopoles for that.

It could be done with isolated magnetic monopoles, I suppose. Unfortunately, they seem to be out of stock at all of the popular suppliers, and I have my doubt whether the brokors who post at DigElementaryParticles.com can actually deliver.

Without the use of monopoles, I suspect that you'll run into the same problem which prevents truely isotropic antennas from ever being built... there's no way to construct the resulting field without having a discontinuity in it somewhere.

You can build an isotropic loudspeaker, but unfortunately space doesn't support EM pressure waves.

You can make a spherical electric field, and maybe spherical gravity waves.

Suppose you put a small conductive sphere inside a bigger conductive sphere. If there were an AC voltage between them, you'd have current flowing from the inner to the outer with perfect symmetry. Would that induce a corresponding magnetic field inside? I suppose not... everything would cancel. And besides, there's no way to apply the voltage to the inner sphere without breaking the symmetry.

I suppose I ought to get back to work. Trying to get a Spartan6 to configure from serial flash, no luck so far.

John

I am sure that magnetic and electromagnetic planetoids not orbiting any nearby star would have a fairly spherical flux/field propagation. It would have to be pretty far away though.

Is this the start of creating a (spherical) force field, similar to that alluded to in some SF stories? In short, how close are we to doing anything like that NOW?

The question is: is it an INNIE or an OUTIE?

It's a common commercial item. Called a 'ball bearing', sphericity is available in high accuracy, forces on the exterior can be quite high without causing any distortion.

Of course, in SF stories, sometimes there's a force field that has lots of other properties than 'spherical'. Like, the field is bigger than the generator, it turns ON and OFF easily... stuff like that.

May the farce be with you! ;-)

ny

Dang, do you have anything useful to say?

George H.

If you find wrong to be useful.

Yes. How is this, asshole?

Your bloodline should be erased from the world, and all of the souls your bloodline has stolen from the hall of souls should be returned forthwith.

Gather your entire family in a car, and drive off a tall bridge immediately. Make sure that you survive long enough to watch all of the others die, right before you return your stolen soul, you worthless piece of shit.

Knowing that someone is always, absolutely, 100% wrong *is* useful.

John

Shucks, you say that to all the boys.

John

Jut saw one end off a bar magnet. ;-)

Clever. About how far is it from the "N" pole of the earth to the geographic North Pole?

Best regards, Spehro Pefhany

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Are these all dimbulb? And surely he must be right every once in a while?

George H.

(If you don't post your name you're a wimp.)

"The Journey is the reward"

eff.com

Hey I know the answer to that, The north magnetic pole is near the south geographic pole. (which you soon* figure out if you try to use the Earth's field as a reference.)

George H.