Re: Misconceptions and static electricity

[GARY HEMMINGER <Hemmig@D-E.PVT.K12.NJ.US>]

> My situation is abnormal: the purpose of the voltmeter is to shatter the
> misconceptions of a person who believes that "static electricity" involves
> only surface charge, and has nothing to do with high voltage.  (This
> misconception is not rare.  It is caused by the teachings of K-12
> textbooks where qualitative attraction/repulsion forces are repeatedly
> emphasized, but the actual magnitude of the potential between the objects
> involved is never mentioned.)
A related and perhaps larger issue is the relation between static and
current electricity,  and common misconceptions that are of course
not unrelated to the fact that at the high school level these
connections often aren't taught at all.
As suggested in "Electric and Magnetic Interactions" by Sherwood and
Chabay one can show a connection between static and current
electricity by demonstrating that the wires in a simple series
circuit in the steady state have surface charge that varies with
position in the circuit.  The surface charge near the positive
terminal of the battery is positive and so on.   I do this with
surplus laser power supply, approx. 11,000 V (and only $15!) and a series
circuit of 4 resistors, each about 10 Megohm.   Use bare wires for the circuit,
and a pith ball clearly shows the surface charge and how it varies.

*****************************************
  Gary Hemminger
  Dwight-Engelwood School
  315 E. Palisade Ave.
  Englewood, New Jersey
             07631
  e-mail: hemmig@d-e.pvt.k12.nj.us
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