Re: Leaking 'Static Electricity'

[Karl Trappe <trappe@PHYSICS.UTEXAS.EDU>]

Thanks, Chuck, but I'm still a bit confused.

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

> > > Regarding the humidity leaking charge explanation:  What is the accepted
> > mechanism?   I know my electrostatics demos don't work when the humidity is
> > high, so I am guilty of saying that the charge leaks off....Karl
>
> Nothing wrong with leaking charges. It just leaks along slightly conductive
> SURFACES (not thru thge air (unless there is an unusually high density of
> ions around.)
>
> Anti-static dryer sheets seem to leave a SMALL amount of hygroscopic
> 'chemical' on the fabric which allows enough conductivity to discharge the
> fibers.
>
> It's no accident that stressed          Chuck Britton
> spelled backwards is desserts.          britton@odie.ncssm.edu

Dr. Karl I. Trappe                              Desk Phone:  (512) 471-4152
Physics Dept, Mail Stop C-1600                  Demo Office: (512) 471-5411
The University of Texas at Austin               Home Phone:  (512) 264-1616
Austin, Texas 78712-1081