Magnetic fields within a toroid inductor.

[MileHigh]

Xee2:

?? If you draw the line integral anywhere inside the toroid will it not always enclose the same amount of current?

Yes but if the summation of all of the dl's is larger then the B has to be smaller because there is a constant amount of current inside the dl loop.

So that's telling you the larger the dl loop the smaller B has to be.  (no pun intended lol)

MileHigh

[poynt99]

Ok,i was refering to the cross section center of the core itself-not the air hole in the middle of the toroid.
So if the magnetic field is strongest within the core itself,why dont we put the secondary coil in the center of the core?,rather than around the outside with the primary winding, like a standard transformer. Dose anyone know what would happen with the secondary placed inside the core itself?. Would this reduce or remove any BackEMF that would effect the primary?.

Brad, in theory it does not matter how loosely the secondary is wound on the core, as long as it loops completely around it. Remember, it is not the magnetic field that induces the emf in the secondary, it is the resulting electric field which does. And this electric E-field emanates from the center of the core outward to OUTSIDE the core itself.

There is another thing about the toroid coil that may answer another debate that was raised in another thread(MH will know this one im talking about) It is in reguards to this bloch wall claim.If it exist within a PM or EM,then it must exist in all PM's and EM's. So when we pass current through a toriod inductor,where exactly would this bloch wall be? Is the toroid the perfect example of magnetic fields looping around a magnet,without this bloch wall?

There is no Bloch wall in a regular PM or EM. And this includes a toroid coil; there is no Bloch wall there either.

[hanon]

So what dose the magnetic field look like within a toroid coil?. Is the magnetic field contained within the toroid core?,and wich field is it-north or south?.
My first test looking at a field being expelled outward from the toroid coil.But listen carefuly to the video near the end.
http://www.youtube.com/watch?v=WNOtEDkCSpA

Hi,

Very interesting!!

Does anyone know why the induced voltage into the external coil has an exact  90º phase shift ? Could you test what happens at lower frequencies as 60 Hz or so?

Is is possible that you are getting in that video another type of induction?

[xee2]

Xee2:

Yes but if the summation of all of the dl's is larger then the B has to be smaller because there is a constant amount of current inside the dl loop.

So that's telling you the larger the dl loop the smaller B has to be.  (no pun intended lol)

MileHigh

MileHigh,
I think I see your point. Since the toroid walls are not parallel like a solenoid, the magnetic field will be stronger near the inner edge of the toroid than near the outer edged of toroid. Thanks for the corrections. I hope I have it correct now.

[tinman]

Mags and tinman,

Forget about toroid coils for a moment, and consider this thought experiment.

If you had a very long solenoid coil, say 1" in diameter and 1 mile long, wound evenly along the entire length of the solenoid, and you energized the solenoid. Would you be able to detect any magnetic field anywhere around the solenoid, other than at the ends or within its core?

In other words, if you were standing 2640 feet from one end of the solenoid, and you had a Hall sensor with you, would you detect any magnetic field anywhere near the solenoid (assuming you could not probe inside it)?

Well i believe that the fields must always loop from one end of the magnet(inductor) to the other,so a magnetic field should be detectable along the outside. The same go's for any length of straight wire that has current passing through it,there will be a magnetic field along that wire.If we look at the power line's that deliver our power to our home's,we know we can light a CFL from the magnetic radiation from those wires. The wires are also twisted to form loops,like that of an inductor-only the twists arnt as tight as they are in an inductor.