Ignition only

[Buchholz, Steven]

Ohm's law directly aplies only to circuits which contain purely resistive
elements.  If you take your ohmmeter and apply it to the "terminals" of a
spark plug you should find infinite resistance.  The spark plug works by
ionizing the material in the gap to form a conductive path by supplying a
high enough potential across the electrodes.  It is the voltage required to
ionize the insulating material between the electrodes that changes with the
density of that material.  

You are most definitely correct in your last statement though ... assuming
that it is a perfect serial circuit.  Whatever current is running through
the gap on the "active" plug is also flowing through the plug receiving the
"wasted spark."  

HTH!
Steve Buchholz
San Jose, CA (USA)

> 	I have a non-EE explanation.  Based on Ohms law, which should apply
> here.  Let's assume the coil has the ability to only put out a set
amperage
> per fire and that amperage has to go across the spark plug on each side.
> Use V=IR.  The cylinder with higher pressure will have a higher voltage
for
> the same amperage.  The cylinder with the lower pressure will have a lower
> voltage for the same amperage.
> 
> As an fictional example:
> Combustion side.  40,000V = 10000ohms*4amps
> Waste side		5,000V = 1,250ohms*4amps
> 
> 	Same current passing through both of them... it is just like a
> series circuit with the voltage source in the center as I see 
> it.  If this is wrong, please tell me why.
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