Re: Sparks - an experimental approach.

[brian whatcott <inet@intellisys.net>]

At 11:52 9/5/98 +0100, Ludwik Kowalski wrote:
> ... Partial vacuum at low E (when Ohm's
> law is applicable) is a better insulator than dry air under normal P. I am
> assuming that free charges are due to cosmic rays only. We are referring
> to different conditions, low E and high E. Sparking, of course, happens at
> high E.


Well, well, well!
 Rather than getting hot and righteous, this offers me the perfect 
opportunity to demonstrate the superiority of the scientific method 
over testosterone:

Take a low voltage filament lamp and break the glass bulb.
Mount it in a bell-jar, mason-jar or some such with an adjacent anode;
the three electrodes are led through the lid along with an airline.

   For a modest pressure reduction provided by a salvaged compressor
from a domestic fridge (or perhaps you have access to lab vacuum?) 
measure the anode current in the microamp range with the filament 
glowing faint-red, the anode held at say nine volts and the 
vacuum varied.

 I fancy one will need to consider factors other than cosmic rays.

Ah, but I hear you say, this is 'thermionic' emission.
   Might you then replace the filament with a sharp point?

    But *I* am not the one who should be convinced, rather the teachers
 of the up and comers...

Best Wishes

Brian


brian whatcott <inet@intellisys.net>
Altus OK