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Re: Elementary Inductance.
Hi Jimmy,
In layman's terms, the length and number of turns determines the inductance.
This is because inductance = induced voltage when current varies (flux cutting
across conductors). The longer the length, the more magnetic flux lines can
impede the conductor to produce more induced voltage. In a "coiled wire", the
flux lines are concentrated impeding more flux lines per area of the inductor
thus producing more induced voltage than an equivalent length of strait wire.
However, all the things you mentioned will play a roll, with length and turns
being the most significant. This one reason why it is simple enough to make a
primary out of scrap wire to get a ball park length for the final version.
Using a larger size of scrap will just get you that much closer. You could even
take this one step further and measure the inductance of the scrap wire, then
make your primary to match the inductance (always leave room for tuning
though).
The proximatey to the coil and it's natural attributes (helical, flat, conical)
will determine the coupling. Typically, a spacing of 1.5 - 2.5 inches are used
between primary and secondary. Our coils are "loosely coupled" and coupling
coeffients are in the realm of 0.08 to 0.25. There is no easy way to calculate
(that I've found) coupling without measuring or without a program which can
step through and define mutual inductance then calculate coupling from the
mutual inductance. I personally feel measuring would be the preferred method if
you really wanted to find out.
Bart
Tesla List wrote:
> Original Poster: "JimmyD" <jim_del-at-email.msn-dot-com>
>
> I know this is an elementary question, and that it may have been answered
> before on the list but,
>
> In _lay terms_ , what determines the inductance in a coil?
>
> The diameter, the height, the guage of the wire, the number of turns or the
> length of the wire?
>
> In tesla operation what is the relationship of the primary to the secodary?
> The guage? The number of turns? The diameters? The heights?