Re: first coil

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

Original poster: "Antonio Carlos M. de Queiroz" <acmq-at-compuland-dot-com.br> 

Tesla list wrote:
 >
 > Original poster: "Dr. Resonance" <resonance-at-jvlnet-dot-com>
 >
 > The basic laws of electrical circuits still apply, even Ohm's law has an
 > effect on RF currents.  If you are trying to stuff 200 Amps through a 12 AWG
 > wire it will retard the current somewhat even if the time period is measured
 > in microseconds.  It's the current that is responsible for creating the
 > magnetic field, not the potential.

This is the effect of inductance, not resistance. A thicker wire
has somewhat smaller inductance, but the decrease is proportional to
the logarithm of the wire radius, and quite small.

The inductance of a straight segment of wire with length d and radius R
is (assuming uniform current):

L=(u0*d/(2*pi))*(Ln(2*d/R)-3/4), u0=4*pi*1e-7

#12 wire has a radius of 1 mm. 1 m of this wire would have
L=2e-7*(Ln(2000)-3/4)=1.37 uH
#4 wire has a radius of 2.6 mm. 1 m of this wire would have
L=2e-7((Ln(769)-3/4)=1.18 uH

Antonio Carlos M. de Queiroz