Magnetic fields within a toroid inductor.

[xee2]

Here is a thought experiment:  You have a 10-meter length of straight wire.  So that's an inductor.  You put 10 volts across the ends of the wire and let's say 10 amps of current flow.  It takes a short while to overcome the inductance and build up the magnetic field that surrounds the wire.  So we know that there is a certain amount of energy stored in the magnetic field around the wire.

Now, lets take the same same wire and make a 180-degree bend at the 5-meter point so that the wire is folded over and the two ends of the wire are right next to each other.  You put 10 volts across the terminals and 10 amps of current flow.  However, there is a huge difference here.  The parallel halves of the wire create magnetic fields that mostly cancel each other out.  Therefore the inductance for this wire configuration is much much smaller than for the straight wire.  Therefore the current rises to 10 amps much much faster, and there is much much less energy stored in the magnetic field around the wire.  So there is no "energy that was always there" in this configuration.  There is simply less energy from the get-go.  Everything balances out like it is supposed to.

MileHigh,

Agreed. I guess we were not talking about the same thing. Thanks for your interesting discussions.

[MileHigh]

Perhaps just a few closing thoughts on on some of the topics.

The analysis of the toroid using Ampere's Law was based on an "air" toroid.  Of course that's the hardest one to set up to not emanate any magnetic field and you need "perfect" symmetry in your coil windings.  Once you add a high-permeability core to the inside of the toroid then things get a lot easier.  The core is going to channel the magnetic flux and offer a much "easier" path than the free space outside the core.  So a decently wound toroidal coil around a toroidal core will produce a near near zero field outside the toroid.  Even just doing a partial wind (totally broken symmetry) and leaving a lot of the core bare will still barely emanate a magnetic field to the outside free space.  The point is to understand the harder problem first, and appreciate the fact that even without a core the toroid will not emanate much of a magnetic field.  And for the sake of completeness note that the analysis that was done for the air core toroidal coil was only done in the horizontal plane of the toroid that cuts it in two like a bagel.  The analysis doesn't say anything about what the magnetic field looks like outside of the center plane of the air toroid.

Also, note that I mentioned the "secondary" magnetic field.  So you draw a different Amperian loop.  This one is at a right angle to the plane of the toroid and it cuts right through the center of the doughnut and encircles the tube of the toroid.  That Amperian loop sees current so you know that there is a secondary magnetic field through the doughnut hole of the toroid.

I may have been able to decipher Dave45's thinking.  Dave45 please comment to correct me if I am wrong.  I will take a chance and state this.  He may have seen the thought experiment with the wires with DC current and just instantly related it to his experiments with coils in ice.  So perhaps he just superimposed what he thinks his coil and ice experiments were telling him and "forced" the same conclusions on my thought experiment?  That's kind of like a bull in a China shop.  The two things are not related at all.  Here is another hypothetical.  Dave45 stated that there is no magnetic field around one of his setups.  Let's take the example of the photograph of the vertical glass cylinder with the vertical coil embedded in ice.  If you run DC current through the coil and move a horizontal hand-held compass around the vertical glass cylinder there is a good chance that you could get thrown off and not detect the magnetic field generated by the coil!  You would have to lay the glass ice cylinder out horizontally to measure the magnetic field.  You also have to be sure you are running enough current through the coil so that the magnetic field generated by the coil generates a magnetic bubble in the Earth's magnetic field.  Dave45 offers up next to zero information so I am just speculating.

MileHigh

[tinman]

Well,looking at the video you posted MH,it's good to see the eskimo's have gone up in the world with there igloo's.

Anyway,im quite supprised Dave45 could get the water to freeze,having a heater in the middle of it. Must have been very low P/in,so as the coil didnt get hot-or even warm.

Now how exactly dose the coriolis effect work in a bathtub(when you pull the plug)-when the object is fixed and traveling with the rotating mass?.

[Dave45]

Just to clarify I checked the coil for a magnetic field before I put it in water, horizontal, no magnetic field.
The coil was powered with 12v dc using an automotive bulb pulling 2 amps.
Iv froze alot of coils using different types of water, bottled drinking water works best for clarity.
Something I found strange if the bulb is placed after the coil, on the pos side it will kill the power supply, its like the coil draws on the supply, the bulb acts as a limiter (resistor) keeping the coil from pulling on the supply, very strange. I killed three or four power supply's before I found this out.
If the coil is placed horizontal in the ice it distorts the fields, the earth has an effect on a coil, all coils in your experiments should be in a vertical position so the fields are not distorted, if you remember the TPU would not work if positioned wrong this is because of the distorted fields, that and the TPU draws energy in one end and passes it out the other.
Alot can be learned by placing coils in water and freezing them, it takes about 24 hours for one to freeze solid but it you check the cell about every hour you may see some interesting results.

The coil winding I showed, not this specific one, but one like it.
The core was rusted and the rust spread and settled in the bottom of the container, the coil spun the water and cleared the rust in the bottom this was at about five or six inches from the coil, do you realize how much force it took to spin the cold water, this was a strong spinning field.

This post was posted in haste Im kindof in a hurry
later
dave

[Magluvin]

Hey Dave

So you use the light bulb in series with the coil to limit the current?

Here is what I think some are thinking, and I question it a bit also. Its natural to question. 

The coil is producing a certain amount of heat. This will cause currents in the water, up and down, all while the freeze tries to solidify.  Its a logical thought considering.
At my work, when the painter has cleaned out his gun into a container, and the paint was a pearl, it ends up a liquid of lacquer thinner tainted with paint color and pearl. If I take that container and set it in the palm of my hand, the top surface of the liquid seams to come alive. Swirling fractal waves coming up from the center spreading outward across the top surface. Put your hand on the side of the container and the swirls come up from that side. So its not hard for me to believe that heat may have something to do with it.  Possibly

Are these vector fields able to go through glass? If so, here is what I suggest.  Fill your container to the top and set up the coil on a horizontal axis facing the jar. The distance should be close to the jar optimally, but heat radiates. Maybe freeze the coil in a block first, then place the block right next to the jar. If you still get swirls in the jar, then I would have much more confidence in saying that it is not heat causing it. Or make a framework that the coil is mounted in the middle and shelves you can put one jar below the coil, one above and one left and right. If there are mostly only swirls in the top jar, then heat is rising and causing it I would say.

Just thoughts on how you could get people to understand that fields are really doing it instead of the first possible thought by others of the effect being caused by heat.

Mags