Beat Frequencies in Bifilar Coil

Hmm ... or perhaps any 100Hz beat component is instead cancelled out (suppressed) by the opposing currents?

Ken Morrow

The currents won't oppose a great deal of the time.

As to the iron core, if one of the sources cause the core to saturate, then you will get mixing.

Mikek

What motivates these "magnetism is magic so let's ask the experts" questions, anyway? I'm curious.

Tim

-- Seven Transistor Labs Electrical Engineering Consultation Website:

No.

Unlikely. To get nonlinear mixing, the field would have to be high enough to saturate the iron

Sounds like a homework question. What class? Mark

It does no great harm to help kids with occasional homework questions. They'll flunk out anyhow.

Class size is too big... instructor seeks to find which students should be dropped >:-} ...Jim Thompson

-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

When I was in college, they used chemistry and physics to thin the herd. The attrition rate in the first two years was probably 25% per year. It was rare for anyone to flunk out after the sophomore year, though there were a few that were in so much academic trouble by then that they couldn't hold on.

Things we can't explain are as good as magic to anyone. If you think you are an "expert", tell us what magnetism really is.

Maybe I just had a dumb teacher.

Ken Morrow

Two opposing magnetic fields will tend to "cancel" or distort. If the signals differ, and their radiated EMF's are superimposed, is it not plausible that the distorted field would have a periodicity representative of the difference frequency?

Ken Morrow

In order to create a 100 Hz component, there would have to be a nonlinear element somewhere. There is none in the copper+air case.

Superposition is addition. That process is linear, so it doesn't create any distorton or harmonics or difference frequencies.

The iron core, if the field is high enough to create some saturation, will be nonlinear so can create some harmonics and the 100 Hz difference.

It may do it even on the hysteresis, depending on just how soft the core is.

(Ooh -- soft-core electronics. Today is getting interesting.)

You seem to be equating cancellations with distortions; they are two different things.

"Distortion", in the electronics sense, implies nonlinearities. In the copper + air case there aren't any (unless you're driving things so hard that you get corona discharge or some such). Without nonlinearities you won't get frequency mixing.

So no, if you understand the phenomenon involved, there won't be.

ANY _curvature_ will cause mixing.

Smirk >:-} ...Jim Thompson

Thanks to you and John for clarifying this point.

Now I am going to embarass myself further by asking this question.

Has anyone ever heard of tensor fields? When two opposing forces, such as EMF's interact, a _potential_ is created on the A or longitudinal vector. This occurs "outside" of the classical EM domain and is undectable by conventional instrumentation.

In the case presnted in my original post, it may be expressed at

That is the theory. Any wholesome comments?

Ken Morrow

Wheeler points out that magnetism is the effect of Lorentz contraction of t he electric fields of moving charges. I was never taught that - Wheeler's b ook came out a bit after the time I worked it out for myself as an undergra duate, but when I talked about my insight with other people, it seemed that the idea was well known, but not helpful enough to get talked about in und ergraduate courses.

You don't get two opposing magnetic fields. The voltages at either end of the coil will be different, so you'd get a single current - which you could work out

which will generate a single magnetic field, which will look like 500Hz modulated at 100Hz. There's no non-linear mixing involved.

"Senior Science for High School Students, Part 1 Physics"

A derivation such as you speak of was in the section on electro magnetism.

.... Phil

Do you mean the magnetic vector potential, symbol "A"?

Not "outside" of anything. It's just a different-from-the-usual mathemati cal formalism for describing how charges moving over *here* affect charges over *there*.

And yes, it's detectable. Aharanov-Bohm effect:

and yes, that is "outside" of Classical EM, but QM's mathematical abstrac tions are as real as any other mathematical abstractions (H and B field, D and E field, etc.) if you can use them to reliably detect and manipulate st uff, which you can.

The foregoing responses still apply. The B field is the curl of the A fie ld and since the B field under consideration is the linear superposition of the 200 Hz and 300 Hz fields, then absent any overdriving or nonlinearitie s in the hardware there will be no harmonics or sum/difference products see n in the A field.

Mark L. Fergerson