Mike, here it is. The resistivity of amorphous carbon is 35 u ohm meters
(That's a 1 meter cube) A 1" cube has a resistivity of 1.4 m ohms, a one inch sphere about 3 m ohms. 100 kA for 20 us dumps 600 J into it. The density of carbon is 2.3 g/cm cubed The 1 inch sphere has a mass of 20 grams The specific heat capacity of carbon is 700 J/kg k The observe heats 43 deg C Dave WX7G On Jul 27, 2012 2:18 PM, "Mike Waters" <[email protected]> wrote: > Man, I don't know, Dave. How long have they been selling those carbon balls > for that purpose? > > I don't have the figures in front of me, but carbon has a significant > amount of resistance. (Maybe that's the secret: the current gets limited as > a result. :-) > > It would be interesting to calculate the resistance of a carbon sphere > sometime (how big are those?). Then we could roughly estimate the voltage > drop across it and so come up with a ballpark figure of the instantaneous > power dissipated in those balls. > > At that point, someone with way too much time on their hands could estimate > the temperature rise based on the specific heat of carbon. :-) > > 73, Mike > www.w0btu.com > > On Fri, Jul 27, 2012 at 2:42 PM, DAVID CUTHBERT <[email protected] > >wrote: > > > www.rossengineeringcorp.com/toroids_spheres_corona_nuts.htm > > On Jul 27, 2012 9:43 AM, "DAVID CUTHBERT" <[email protected]> > wrote: > > > >> <http://www.rossengineeringcorp.com/toroids_spheres_coronary_nuts.htm> > >> > >> Ross recommends carbon for lightning. > >> On Jul 27, 2012 9:33 AM, "Mike Waters" <[email protected]> wrote: > >> > >>> I don't think carbon balls are suitable for lightning protection. Think > >>> of > >>> the voltage drop that would appear across each ball during a direct > hit. > >>> I > >>> think they would vaporize. > >>> > >> > _______________________________________________ > UR RST IS ... ... ..9 QSB QSB - hw? BK > _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
