Re: Leaking 'Static Electricity'

[Ludwik Kowalski <KowalskiL@MAIL.MONTCLAIR.EDU>]

The term "leaking Q" is often used instead of "neutralizing it with ions
which come from air". No matter how dry air is an electrostatic demo will
often not work near a burning candle. An electrified comb will be
discharged in a second near a flame (for example 2 or 3 cm away,
sidewise).
Try this demo in front of a class and ask students to guess what happens.

Is there any reason to think that humid air normally contains more ions
than dry air? If not then Karl's mechanism must dominate.
      Ludwik Kowalski

      Karl Trappe wrote:
> If I understand you, my VDG discharges along its column, not through the
> air.  That is a plausable explanation to me.  Does this mean that the
> *humidity* supplies the "solution" to allow the junk on the column to start
> an ionic conducting path?
>
> Certainly, I believe that oil and grime (usually from hands which picked up
> the VDG by the column) provides a multi-megohm resistance path from the
> sphere to the base (via the small cracks in the column which result from
> static produced ozone interacting with the plastic of the column).  I have
> been able to dramatically improve performance by cleaning the column with
> alcohol, and allowing the alcohol to evaporate.
>
> I also know that on a high humidity day, that static electricity demos
> don't work.  Some "crisp" weather parts of the country never have this
> problem.  I even keep all electrostatic demos in a dry cabinet with light
> bulbs burning 24 hours a day to insure their dryness.
>
> I realize that water, as a polar molecule, is not generally a good
> conductor (unless "dirty", and thus ionic), although it is an excellent
> dielectric when clean.  Clearly, suggesting that warm, moist air ("clean
> water carrying" air) is a good conductor makes little sense to me, but I
> don't have a better explanation.
>
> My confusion is that if I run a (cleaned column) VDG, or run a comb through
> my hair, I get good results when the air is dry.  If I open the door on a
> humid day, both of these "clean" sources cease to produce static charge
> separation.
>
> So...I'm all ears for a "clean" explanation.  Karl