# Circular current in a toroid

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If this isn't the best sub-forum for this question let me know

Let's say you have a ferrite toroid (donut) ring and I wanted to induce a continuous circular current in that toroid. What is the simplest coil configuration to make this happen.

I know that a spinning permanent magnet in the center of the toroid would accomplish this, but I find that a bit cumbersome. So I would like to find a coiled wire alternative. Hopefully it will be of simple geometry.

Thanx

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Continuous, as in DC? You're going to run into a problem with that. $V = -\frac{d\phi}{dt}$. You'd need a continually increasing field.

But if you want AC, then a coil around the toroid (aligned along same axis) will work.

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Yea, I meant DC power. As far as the power having to increase for DC power to keep inducing a current, can it be pulsed DC to avoid this to keep the electrons moving around in the toroid?

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Mr Skeptic.....Shhhhh, that's what I'll actually be using

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Hm, then place your toroid in a magnetic field such that magnetic field lines pass through the center, cool it so it superconducts, and remove it from the magnetic field (or let the magnetic field collapse). Obviously, if this is not a superconductor, the flow of electricity will come to a halt. Placing it inside the magnetic field will induce a current in the opposite direction, which is why for a superconductor you have to place it in the field before making it superconducting.

If you want current in one direction only without a superconductor, you may be able to accomplish that regardless. You'd need to put diodes on it.

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What I would like to do is make the cooper-pair electrons in the superconducting toroid go continuously in a circle in one direction. I know that if I put a rare-earth magnet too close to a superconducting toroid (SCT) while it is below Tc, then the magnet will be pinned and very hard to move against the field lines.

But if I move that magnet just an inch or so further away from it, It should be easier to cut the field lines around the cooled SCT ring.

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Mr Skeptic.....Shhhhh, that's what I'll actually be using

Why didn't you say so in the OP? You just said ferrite.

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Cause I work for a secret agency....then I got fired for spilling secrets like a moron

But seriously, I wanted to keep the focus for the time being on how to move current in a toroid around and around in a single direction.

Usually whenever I mention superconductors people tend to ask other questions instead of focusing on the main one.

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But seriously, I wanted to keep the focus for the time being on how to move current in a toroid around and around in a single direction.

The problem is that the answer is different if you use a superconductor, since you don't need to maintain a potential difference. So you get the wrong answer by omitting the information.

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Ok, ok, sorry for the misdirection but what I'm getting at is seeing if there is a way to move the more and more cooper-pair electrons around the toroid to reverse-produce a gravimetric field. Read the article below to see what I'm getting at:

http://www.newscientist.com/article/mg19225771.800

I know that many things in nature are reversible such as an electric motor, it can produce work when power is put into the motor OR make power when work the shaft is made to spin.

I'm just seeing if there is a way to have the SC stay fixed and not move while applying an EM field to simulate the SC toroid moving. Maybe I'm on "sci-fi crack". But I have searched the web up and down and found no other similar experiments.

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what the hell is a 'reverse gravimetric field'

the article you linked to is about gravitomagnetism, a predicted effect of general relativity. you won't be able to measure anything as the effect is absolutely tiny and its only recently we've been able to achieve the accuracy needed to put it to the test.

it will not result in an antigravity device if thats what you're thinking.

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The article explains that the effect is gravitational, not magnetic. It's named gravitomagnetism because the gravitational equations look like magnetic field equations. This is explained early on in the article

Despite its name, gravitomagnetism has nothing to do with magnetic fields as we think of them. According to Einstein's general theory of relativity, a rotating mass such as a planet should twist the fabric of space-time, and any object nearby should be dragged around by the vortex. It is really just another case of matter telling space-time how to curve and space-time telling matter how to move. Just as a stationary mass creates a "dip" in space-time that we perceive as gravity, a rotating mass creates a twist in space-time.

The discussion of magnetic fields and superconductors was in the context of measuring the spinning of the gyroscopes.

The article does contain one egregious error I spotted. "Janet Tate, now of the University of Oregon in Eugene" Ugh. Prof. Tate is at Oregon State (she's the wife of my thesis advisor, and her lab was up the hall from where I worked. I TA'd for her one semester.)

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As far as magnetic fields in SC's go, when they spin fast enough, they mysteriously manifest their own magnetic field on the same axis as the SC spins. This is known as the London-moment.

From what I read it is not known why this happens with SC's, But I think that the spinning SC's are actually interacting with the earth's natural magnetic field. Since the earth's magnetic field is so relatively weak you would have to spin the SC at 5000+ rpm to see the London moment happen.

The only way to debunk this idea is to take the nobonium-plated gyroscope far into space away from any naturally occurring magnetic fields.

But if this were true then this would explain why the results for this experiment are so inconsistent due to the varying strength of the earth's magnetic field.

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Why not just shield the external magnetic field?

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The experiments I read about never said anything about shielding the discs from natural (or otherwise) magnetic fields. Maybe they do as an act of protocol. Maybe someone can on this board can tell us?

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