🚀 go-pugleaf

On 4/22/95 Gary Karshner <phygary@stmarytx.edu> wrote:

>        Models of real capacitors are, of course just that - models.
>        Q = CV is at best a first order.

Yes, models are only approximations of reality; some are better, others are
worse. But users of models can be TOTALLY WRONG in trying to solve problems.
That is what happens, I think, when a textbook writer claims that a steady
voltage V1 on capacitor C1 (I am referring to two capacitors in series with
a source of constant d.o.p., V) is given by V1=V*C2/(C1+C2). This is true
only for very spacial cases (as discussed in previous messages). The mental
picture of equal static charges, and the formula 1/C=1/C1+1/C2 derived from
it, are total errors in the context of dc circuits.

Several days ago I looking at a new edition of a textbook published in 1995;
the same old myth is repeated. It would not be fair to single out one author;
check the new edition of your favorite text. Why do textbook writers ignore
what was written in The Physics Teacher and what was discussed at several
AAPT meetings? What can be lost by correcting a misconception? They know
that they are wrong and they do nothing. WHY ? ? ?  Authors, defend your
position or change it, please. Who benefits from the conspiracy of silence?

                        Ludwik Kowalski    kowalski@apollo.montclair.edu