William Beatty responded to my question on sparks as follows:
>Our bodies are electrolytic conductors, so
>the "charges" upon our fingertips are sodium
>ions, chloride ions, potassium, charged proteins,
> etc. If we avoid saying "electrons" and instead
>say "excess of charge" or "charge-imbalance",
>then we don't have to discuss the details, such the ions
>which make up that charge.
Fair enough. But wouldn't the ultimate flow of charge through our bodies be
electrons migrating from atom to atom. Admittedly this is not a single
electron making the entire run from foot to finger, but is anything lost by
thinking of it as a single electron.
>You're leaning in the right direction [in talking
>about induced charges]. Another way to say
>the same thing When you bring your
>surrounding E field and make it much stronger,
>and when the field is intense enough, a spark
>occurs.
But which is cause and which is effect. Is not the "compression" of the
electric field a result of the induction?
>But the increasing force upon the "CHARGES" :)
> never grows strong enough to make them leap
>from your finger. Instead the electrostatic force
>applied to the air molecules causes the air to
>'ignite' and turn into plasma, which is a conductor
That's an interesting possibility that never occured to me. But will the
E field actually grow large enough to create a plasma. Is it easier to pull
electrons from neutral oxygen and nitrogen molecules than it is to pull them
directly off a negatively charged finger?
Also, what would account for the light from the spark in the plasma
model? I had always assumed that the "jumping electrons" collided with the
H2 and N2, knocking their interior electrons electrons to a higher energy
level and that the light was emitted in the subsequent decay. In the plasma
model, I imagine that the free electrons would also emit EM radiation when
they reattach to the atoms molecules after the conditions to maintain the
plasma no longer exist. But this I suspect would involve primarily the
outermost electrons and I don't know if the resulting radiation would be
visible light.