Kirchhoff is for the birds...

[partzman]

What i find interesting is that we seem to be unable to shield the secondary from the electric field.
Dose no one else find this interesting ?.


Brad

Well, I'm certainly no expert but it seems to me that the secondary induction is not caused by the primary's E field but rather by change in the magnetic vector potential or A field in the center of the toroid over time or dA/dt .  The question then would be- is the A field able to be shielded?

Those much more knowledgeable that I should refute or confirm this! 

Pm

[Smudge]

Well, I'm certainly no expert but it seems to me that the secondary induction is not caused by the primary's E field but rather by change in the magnetic vector potential or A field in the center of the toroid over time or dA/dt .

It isn't just the A field at the center of the toroid (although it has maximum value there) but the whole circular A field that goes around the core and passes through the center (as does the secondary conductor).  IOW there is an A field alternating in value hence an E field all along the secondary wire.

The question then would be- is the A field able to be shielded?

No it can't be shielded in the normal sense of a shield.  But it can be almost negated and the easiest way to do this is to make the shield a shorted turn.  Then the current induced into that shorted turn produces an additional A field that opposes the original one, and that opposing A field has curl so there is also a B field opposing the applied B field in the core.  The poor old primary now has a hard time trying to drive any flux into the core.

Smudge

[partzman]

Thanks Smudge!

Pm