Re: First EM lab

[Brian Whatcott <inet@INTELLISYS.NET>]

At 05:09 PM 1/13/02, Brian McInnes wrote:
> on 14/1/02 8:20 AM, Joseph Bellina at jbellina@SAINTMARYS.EDU wrote:
>
> > If you estimate the radius of the pencil point, and you know the maximum
> > E field before an arc can occur in air, then you can easily estimate the
> > charge on the pencil point.  Alternately, having previously shown that
> > about 1 in 100,000 surface sites on the tape is charged, you could make
> > a reasonable estimate of the charge on the pencil point.
> >
> >
> And, if readers are intrigued by the esoteric-looking clues being dropped
> all over the place, take yourselves to the library or to Amazon ($78.10 well
> spent) and look at Matter and Interaction: Electric and Magnetic
> Interactions by Chabay and Sherwood
>
> Brian mcInnes


This is just too much money to spend in order to satisfy my idle curiosity -
so I'll have to give a wild guess - nothing like a wrong number to bring the
corrections out....
A plastic pen can hardly have a capacitance greater than 3 pF, and vigorous
rubbing could generate 20kV I suppose: that's Q =  3E-12 X 2E4 = 6E-8 C
= 60 nanocoulombs.
How'd I do?






Brian Whatcott
  Altus OK                      Eureka!