Magnetic fields within a toroid inductor.

[Magluvin]

The idea is to understand that there is a changing (increasing and decreasing) B-field within the core. This changing B-field is created by the primary coil and is "conducted" all the way around the core by the core material. Since the secondary happens to be in the direct path of this changing B-field, the resulting changing E-field around the secondary (in the same plane) causes the secondary induced emf.
Correct. The E-field is a product of the changing magnetic field. The changing magnetic field from the primary is caused by current in the primary, which of course is caused by voltage applied to the primary coil.
I mean that the flux "travels" around via the core to the secondary, where it goes through the "hole" of the secondary coil.

There is an E-field produced at every point around the toroid (perpendicular to the B-field), no matter if there is a coil situated there or not. When we properly place a coil in the path of the B-field, the coil "intercepts" the resulting E-field and hence has an emf induced in its windings.

Hey Poynt

Have you read the pdf I posted? I put it here again.

When you have time. If you havnt, please check it out. It makes a lot of sense.

When a wire has a rising voltage imposed upon it, a B field expands around the wire. So in our primary, the individual wires are the origin of the magnetic field produced by input. So why is that not the case with a toroid transformer, or any other closed core transformers? How could ther not be any flux outside of the core in those windings, where the flux originates? 

If you havnt read the pdf, give it a gander.  18 pages. Let me know what you think.


Thanks

Mags

[Magluvin]

Hmmm, just thought of a good example. Hopefully. 


If we have a straight rod core with a coil wrapped around it, we can understand that the inner parts of the flux loops of the coil will be in the core and out of the ends, they loop out expaded in space/air.

Now lets take a C shaped core and wind just on the left of the C, in the middle leaving some length of the core, top and bottom of the C without wire on it. Now imagine, from what you know, what do the fields look like now?  There should be much stronger flux between the upper and lower C core legs, and then anything outside of the C as a whole is less dense.

So now, we close off the C core into a toroid. Can we not see that the flux crosses over the open space inside the toroid hole as the field expands from the primary?


Mags

[poynt99]

Mags.

I read Distini ages ago, and I re-read some of the one you posted. I think he has some incorrect notions.

The B-field around the individual wires combine to form a concentrated field within the core. Beyond the surface of the wire itself, there is very little flux.

Build a toroid coil and get a Hall sensor to test it out yourself.

[Magluvin]

Mags.

I read Distini ages ago, and I re-read some of the one you posted. I think he has some incorrect notions.

The B-field around the individual wires combine to form a concentrated field within the core. Beyond the surface of the wire itself, there is very little flux.

Build a toroid coil and get a Hall sensor to test it out yourself.

I got some hall sensors coming this week. 

Thanks for your time Poynt.

Mags

[tinman]

So am i right in understanding that the current loop is strongest at the center of the toroid core? or is it the magnetic field that is strongest at the center of the core-or both?.