Re: Quarter Wavelength Frequency

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Original poster: "Bob \(R.A.\) Jones" <a1accounting-at-bellsouth-dot-net> 

Hi Shaun

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Tuesday, July 06, 2004 3:45 PM
Subject: Re: Quarter Wavelength Frequency


 > Original poster: biomed-at-miseri.winnipeg.mb.ca
 >
 >
 >>  >length has no significance (an understandable mistake).
 >
 > Wire lengths only affects the number or turns you can put on a form for a
 > given diameter of the form!  Each turn of a selenoid is magnetically
linked
 > to the adjacent turns of the selenoid, hence inductance occures within the
 > selenoid.  Capacitance occures between the adjacent turns of the coil
 > because of there physical proximity and the fact that there is a voltage
 > difference between them.  These two elements, mutual inductance and self
 > capacitance, set the resonant frequency of the secondary coil, not the
 > wavelength the wire used to wind the coil.  The wavelength formual is for
a
 > straight wire, not looped like in a coil where inductance comes more into
 > play.  Granted there is a small amound of inductance and capacitance on a
 > piece of straight wire, which doesn't affect the wavelength formula, or
 > maybe this is where the propagation velocity comes from.  Once you loop
the
 > wire like a coil, you have self inductance and interwinding capacitance!
 >
 > of the secondary.
 >
 > Shaun Epp
 >
Yes it is the self C and L that determine the prop velocity of an open wire.

Given the the fact that the self inductance and capacitance are of a
solenoid are 100s of time different from an open length of it's wire never
the less they change in such a way that the length of the wire in a solenoid
is very approximately (say with in times two for typical coils) equal to the
a 1/4 wave length in free space of the coil's first resonant frequency.

Incedently the adjacent turn to turn C does not contribute significantly to
the self C of  coil. Its mostly the C to  ground and the C between the top
and bottom of the coil particularly so in isolated coils.

Check out Paul's TCSP site for details.

Bob Jones