Date: Tue, 02 Jul 2002 23:55:00 +0200
Author: Adolf Cortel
Subject: Re: Coulomb's Law Apparatus
I wrote one of these articles in TPT ( "Demonstrations on Coulomb's Law with an
electronic balance", 1999 (october), pp 447-448). I use christmas balls, quite
available and cheap, instead of copper balls.
If you read the article and have any question or you want more information,
I'll be glad to send it to you.
IES Pompeu Fabra
Martorell, Barcelona, Spain
Joe Pifer wrote:
> We use an electronic scale to measure the inverse square dependence. The
> apparatus consists of a 2 inch copper sphere on an insulating rod place on
> an electronic scale (at least 10 mg resolution). The sphere is charged by
> induction. A second charged sphere is brought close and the change in
> weight measured as a function of distance. You can also determine the
> charge dependence by repeatedly touching one sphere with an identical
> uncharged sphere. Each time the two touch, half the charge is transferred
> to the uncharged sphere.
> This experiment is based on several articles in the Physics Teacher (that
> I've lost). Rich Fiorillo made this apparatus for us. It's fairly easy and
> cheap to make the apparatus yourself. The only expensive item is the scale.
> If you wish I can send you a MS Word copy of the lab writeup that describes
> the experiment in more detail.
> Joe Pifer
> At 03:10 PM 7/1/02 -0700, you wrote:
> >Our department is looking for a set of apparatus dealing with Coulomb's
> >law in the introductory physics lab. Currently we are using the book
> >ELECTRIC &MAGNETIC INTERACTIONS by Chabay and Sherwood in which playing
> >with Scotch tapes. We tried PASCO's Coulomb Balance but found it's too
> >delicate and we don't feel comfortable with the high voltage.
> >Thanks in advance for any suggestions.
> >Cliff Chen
> >Occidental College