Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx> Hi Jared,Frequency will change the inductance. A "change in magnetic flux" forms an induced voltage by means of the change in current. Tesla Coils and their frequency's are affected by changing currents and the varying waveform is only the beginning. Because the coil is, a coil, there are also changes in current due to the shape and geometry of the coil itself. There are many such causes to current opposition as you know. All of these "changes in current" cause various values of induced voltage along the length of the coil. When all is said and done, you will "not" measure the same inductance at high frequency in a coil as you would with a low frequency inductance, or even a high frequency inductance with a different geometry (yet same length of wire). The difference in inductance is not large, but it is often enough to cause a significant change in frequency. When I refer to the interturn inductance, I am referring to the fact that you will measure different values of inductance along a coils length for the same number of turns (or same length of wire). That is a fact.
When I am referring to interturn capacitance, I am referring to the distribution of capacitance for each turn and how each turn adds to the total effective capacitance. As you know, nearby objects also affect the distributed capacitance as does the ground plane, top load objects, etc. I didn't mean to limit C.
I know that high frequency affects are not well understood by all the list members and I don't claim to have great knowledge of every detail. For everyone I know, this is an ongoing study, and in my opinion, nothing is ever written in stone. There are many ways to look at the same thing. As long as there are no gross missing parts, then fine. Most of us started with wire length theory's and applied it to our coils. However, some major pieces to the puzzle were not being accounted for, and we all knew it. The missing pieces were known, just not accounted for. But, that was then.
Take care, Bart Tesla list wrote:
Original poster: Jared E Dwarshuis <jdwarshui@xxxxxxxxx> The length of the wire has no ability to account for the inter-turn capacitance or inter-turn inductance which is formed by currents within the wire and currents affected by other currents in adjacent turns. This is "ridiculously" obvious. If one must consider these "real" situations, then wire length theory hits a dead end. The bottom line is wire length theory is limited, and we are beyond that limit (but not everyone has traveled down that path). There was a time when coils were built with wire length theory, they worked fine, and the theory was accepted. This list has battled these issues in the past (ref the archives). The fact is, as we strive to understand the physics encompassed with our coils, we realized wire length theory could not provide the answers. If you want to "ball park" these physics, fine. But, if you really want to know, follow the currents. Take care, Bart Hi: Bart Inductance is not regulated by current, otherwise when (we) changed the current(we) would change the inductance. (not so!) Inductance is not regulated by voltage either, otherwise when (we) changed the voltage (we)would change the inductance. (not so!) Capacitance is defined as q/v. (We) must realize that The current in the windings has little to do with inter- turn capacitance; it's the voltage and charge within the inductor that defines its capacitance! When (we) talk about the characteristics of inductors (we) cannot limit ourselves to just current or voltage, (we) must consider: Charge; the first derivative of charge and the second derivative of charge. Va to Vb = - L di/dt speaks of the rate of change of current, not of current itself. Sincerely: (me)