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You may need a new belt. Our Van de Graaff wasn't developing much charge and replacing the belt really helped (even though the old one looked fine) . Make sure, however that it is a NEW new belt, and not one that has been sitting in a drawer for a couple of years.

The rice crispie demo works nicely with bits of styrofoam peanuts also. They don't explode, but they jump off of the volunteers' hands nicely, and this one always works, unlike getting someone's hair to stand up. And it's not quite as messy as rice crispies.

Anna

Anna Hurst
Education Department
Schenectady Museum
15 Nott Terrace Heights
Schenectady, N.Y. 12305
(518) 382-7890 x236


>>> Beryl Rosenthal<[log in to unmask]> 02/17/04 08:31AM >>>
ISEN-ASTC-L is a service of the Association of Science-Technology Centers
Incorporated, a worldwide network of science museums and related institutions.
*****************************************************************************

I particularly agree with the moisture comment.  We have done a demo
with rice krispies exploding all over the place once the charge has
been built up (it makes our curators crazy!), and it ONLY works
correctly if the cereal has been dried out for several days prior to
the demo.
Beryl

>ISEN-ASTC-L is a service of the Association of Science-Technology Centers
>Incorporated, a worldwide network of science museums and related institutions.
>*****************************************************************************
>
>Unpredictability is part of the nature of Van de Graff's.
>
>It doesn't take much for them to stop working or to
>perform really poorly.  Two things are particularly bad
>for building a charge... any moisture in the air and the
>charge will bleed off into the air very quickly... and any
>tarnish or dirt on the ball and it won't hold a charge.
>
>Depending on what your ball is made of (probably
>spun aluminum) you could try cleaning it with an
>alcohol pad (inside and out) before you run it.  Clean
>the belt too...
>
>Good luck...
>
>Dave Taylor
>------------------------------
>
>>  From: Jesse Alexander <[log in to unmask]>
>>  Reply-To: Informal Science Education Network
>>  Date: Sat, 14 Feb 2004 02:56:24 -0800
>>  To: [log in to unmask] 
>>  Subject: VDG Questions
>
>>  Hey Folks,
>>
>>  I'm looking for inexpensive ("pre-owned" is ok) Van de
>>  Graaff generators that can be easily taken on the road
>>  during traveling science programs. I am also looking
>>  for "care and feeding" guides for VDGs.
>>
>>  The generator should be about 24" tall so that it can
>>  be easily seen during assemblies of 300+ kids.
>>
>>  We have had a lot of problems with "unpredictable" VDG
>>  behavior on the road. Something seems to be shorting
>>  out the globe. I can develop a charge by holding my
>>  fingers about a 1/4" from the belt, but the charge
>>  somehow doesn't make it to the globe (once I remove my
>>  fingers-of course). The rubber belt is exposed on our
>>  Pasco SF-9722 VDG.
>>
>>  Any ideas?
>>  Jesse Alexander, WB2IFS
>>  Science Evangalist/Demonstrator
>>  Liberty Science Center
>
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--
Beryl Rosenthal, Ph.D.
Director of Exhibitions and Public Programs
MIT Museum
265 Massachusetts Ave.
Cambridge, MA  02139
Tel: 617-452-2111
Fax: 617-253-8994
[log in to unmask] 

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More information about the Informal Science Education Network and the
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***********************************************************************
More information about the Informal Science Education Network and the
Association of Science-Technology Centers may be found at http://www.astc.org.
To remove your e-mail address from the ISEN-ASTC-L list, send the
message  SIGNOFF ISEN-ASTC-L in the BODY of a message to
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