Magnetic fields within a toroid inductor.

[tinman]

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

Thank you point,and i was with you on this one.MH tried for some time to show this to other's,but-well lets just say,they love there bloch walls.

[tinman]

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?

Hi hanon
I can shift the phase angle from 0 to 180* out,by varing the frequency.At low frequencies,there is no phase shift.Only from about 5KHz dose the phase start to shift. I dont think there is anything to it,but once i hit a 90* phase shift,is when i get maximum amplitude from the secondary.

[MileHigh]

Xee2:

Quoting you:

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.

Yes indeed, and for posterity I am attaching the screen cap of the clip that shows the formula.

Some people may not be comfortable with doing derivations.  But for what it's worth the teacher that made all those wonderful clips I reference from time to time is excellent at doing and explaining derivations.  The essence of a derivation is taking what looks like a very complex problem and reducing it all down to a simple formula.

Some people may also not be comfortable with interpreting formulas and shy away from them.  But if you followed this thread and have a look at the formula in the attached screen capture and contemplate it, it may all come together.

If you look at the formula and the associated diagram in the screen cap and contemplate it for a while, you should be able to see that just the formula itself is telling you that the magnetic field strength is highest along the inside wall of the toroid.

MileHigh

[MileHigh]

Tinman:

I can shift the phase angle from 0 to 180* out,by varing the frequency.At low frequencies,there is no phase shift.Only from about 5KHz dose the phase start to shift. I dont think there is anything to it,but once i hit a 90* phase shift,is when i get maximum amplitude from the secondary.

You might recall that I stated that there should be no phase shift at lower frequencies.  Below 5 KHz your toroidal coil was acting like a single-turn primary to the N-turn secondary of your pickup coil.  This is due to the generation of a separate magnetic field that is not associated with the magnetic field that is generated inside the core.

You cannot ignore frequency effects when it comes to coils and capacitors but that is a whole other can of worms that's not for this thread.

MileHigh

[poynt99]

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.

When the solenoid length is >> than the solenoid diameter, no there will not be a detectable B-field outside the solenoid when you are half way from one end. In fact this will be the case for 99.999% of the length of that 1 mile long solenoid. You WILL detect a B-field outside the solenoid when you are very near the ends.

And so it goes with a toroid. There are no open ends for the flux to "escape" and return, hence the B-field outside the toroid is practically zero. The return path is through the center itself because the solenoid makes a complete circle.