Re: Traveling node - anti-node

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "john cooper" <tesla-at-tesla-coil-dot-com> 

All:  Here's an interesting experiment.  Has anyone out there constructed 
'pick-up' coils?  Tesla used these and I'm thinking of building a few.  Any 
tips on wire gauge to use?  Surely some out there have considered this and 
could perhaps clue me in to this endeavor.

Cheers,

John F. Cooper
Irvine, CA
www.Tesla-Coil-dot-com
www.FrankensteinsLab-dot-com



---------- Original Message ----------------------------------
From: "Tesla list" <tesla-at-pupman-dot-com>
Date:  Thu, 11 Nov 2004 07:50:01 -0700

 >Original poster: jdwarshui-at-emich.edu
 >
 >Hi Phil:
 >
 >The difference between lumped and distributed L.C. are directly
 >analogous to the differences found between simple harmonic motion of a
 >mass and spring and the standing wave resonance found in ropes. In the
 >mechanical world when a rope is at the correct frequency to produce
 >stationary nodes we will find the same exchange between kinetic and
 >potential energy that is found in a lumped mass spring system.
 >
 >When an inductor's wire length is just a tiny fraction of its
 >wavelength we can consider this to be lumped, no standing wave can be
 >produced within this inductor as it is too short at this wavelength to
 >produce the conditions where waves can superimpose to produce
 >stationary nodes. An inductor used this way behaves analogously to a
 >fixed mass in a mass spring system.
 >
 >When the wire length of an inductor matches the frequency we can no
 >longer treat this inductor as a lumped system. Waves traveling (both
 >directions) through the uniform medium of a cylindrical inductor can
 >now superimpose to form stationary nodes. Mathematically we now need
 >to examine this medium as a distributed inductance per length directly
 >analogous to a rope's mass per length.
 >
 >The upshot is that we can no longer look at an inductor the same way
 >as we are accustomed. So for example if we wanted to see two voltage
 >nodes on a given inductor we would no longer use the inductance value
 >of the full length of the inductor but would instead substitute the
 >inductance value of one fourth of the inductors length. For a coil
 >with 1000 turns we would use the inductance (and self capacitance)
 >value of only 250 turns to get a full wave coil (and the entire coils
 >length would need to match the wave length).
 >
 >You can find the formulae to describe L.C. node formation at:
 >http://people.emich.edu/jdwarshui/correspondence.html
 >
 >
 >
 >