Re: series capacitors ...

[LUDWIK KOWALSKI <kowalskil@alpha.montclair.edu>]

Brian asks: 
>             Care to try?
> Cap 1; leads A, B  Value 3 microfarad
> Cap 2; leads C, D  Value 6 microfarad
> Battery 3; pos lead E, neg lead F  10 volts
>
> Procedure:
> Connect cap 1 and 2 to battery 3.  
> Leads B and C to pos terminal
> Leads A and D to neg terminal.
>
> Q's ???

One more qualification is necessary, if one wants to be "practical".
The time during which the circuit is closed must be very short in
comparison with R1*C1 and R2*C2. This was implicitly stated in the
first message (leakage resistances R1 and R2 have no effect). The
ingineers know about the effect of leakages very well; their d.c. 
circuit rule is "not to use capacitors in series unless a parallel 
resistor is connected to each of them to control the distribution 
of charges". 

But physics textbook writer let us believe that Q1 and Q2 are equal 
in the equilibrated (steady) state. We discussed this issue three 
years ago under the subject "a myth about capacitors in series". How 
can I resist to remind you? Messages posted under the thread can be 
found on my home page (see below). 

The basic reference is: A.P. French, The Physics Teacher, May 1993.
Also read E.D. Noll, "Capacitors in series: a laboratory activity 
to promote critical thinking", Physics Education, November 1996.

      Ludwik Kowalski     http://www.csam.montclair.edu/~kowalski

P.S.
In my opinion "public snipings" and "embarassing comments" are
perfectly OK as long as we know that everybody is motivated by the
concerns which unite us on this list. We learn from each other and
this is the most important.