Re: Differences between "bad" streamers and "good" streamers

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

Original poster: "David Speck by way of Terry Fritz <teslalist-at-qwest-dot-net>" <dave-at-davidspeckmd-dot-org>

Sue,

Not impossible at all -- consider Schlieren (sp?) photography which can 
photograph shock waves in wind tunnels, as well as the heat from candle 
flames.  The trick is that the arc does not block light, but instead 
deflects it.

The strobe is essentially a point source, and your arcs make the air hot, 
changing its index of refraction.  In essence, this makes the tube of hot 
air act like a lens.  If there is a fortuitous ratio of distances between 
your flash, your arcs and the screen, you will see a negative image of your 
arc, because the light that was supposed to pass through it will have been 
refracted away.

I've seen similar effects when I run my coil outside for my Halloween show 
-- if I run it while the sky is still light, I can see the waves of 
distortion even though I cannot see the light of the arcs themselves. You 
could get the same effect with a bright light and a propane torch, for a 
more stable effect.

Dave

Tesla list wrote:

>Original poster: "S Gaeta by way of Terry Fritz <teslalist-at-qwest-dot-net>" 
><sgtporky-at-prodigy-dot-net>
>
>Someone took a picture of my coil with flash. You can barely make out the
>streamers. The wierd part is that there was a solid white background in the
>photo, and in two of the photos it looks like there is a shadow of the
>streamers on the wall. That's impossible! Isn't it????? How can something
>that is light + invisable energy block light?
>
>Sue