Where Did It Go? EMF Cancellation Within a Toroid

Question

I have a toroidal transformer with split primary windings. If I connect the two windings so their fields oppose, and apply an identical signal to each, I presume that due to the properties of a toroid there is no EMF emitted.

Yet it appears current is still being consumed.

Silly question: If there is no magnetic field being produced, where is the energy going?

If there is a magnetic field, where is it? Bleeding into the airspace around the toroid?

If so, what does it look like, why is it not contained within the toroid like a normal magnetic field?

No mention of black holes please.

Robert Miller

whit3rd · Accepted Answer

Yeah, of course. You've made a primary winding with zero inductance, the transformer is now a copper resistor. All the impedance of an inductor, that was supposed to keep 60 Hz primary current low when there was no secondary current, is zero. Burn up any fuses yet?

There will be some field in the gaps in the winding, though. Leakage inductance, it's called.

Sylvia Else · Answer

A small amount is heating up your coil. Rather more is probably heating up your power supply. Sylvia.

alien8752 · Answer

Then you have opposing fields within the toroid.

Presume nothing. Probe the space around it.

Where did you insert your ammeters? Did you remember shunt resistors?

Heat, mostly.

Did you look?

Probe it and see.

None required.

Mark L. Fergerson

Where Did It Go? EMF Cancellation Within a Toroid

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