Re: Disectable Capacitor

[sampere <sampere@SUHEP.PHY.SYR.EDU>]

I don't think so.  Charges don't like to move around on insulators, they stay
where you put them!  When you charge a capacitor, you also polarize the
dielectric, you don't charge the dielectric.  That's what gives the capacitor its
capacitance!  Very little charge is stored on the metal cans of the capacitor; you
know this because there isn't a big spark after you separate the cans from the
plastic.  If your scenario was correct, you can have a steady state DC current
through a capacitor.  We all know that I-->0 for t>>1/RC.

Do the electrophorus demo for further proof.  Charge a styrofoam block and set an
insulated metal disc on it.  Touch the disc and you charge the disc.  What is the
charge of the disc?  Opposite that of the styrofoam, you just charged it by
induction.  Prove this with an electroscope.

This time, repeat the above but don't touch the disc. The disc doesn't get
charged.  Why, the charges stay put on the insulator.

You can do this induction demo forever!  Leave the thing out overnight and touch
it in the morning.  ZAP!  Still charged.  Too cool.

Donald E. Simanek wrote:

> The cans touch the plastic dielectric at many places, and the strong field
> between the cans forces electrons from those contact points to the
> dielectric on one side of the dielectric, and from the dielectric to the
> can on the other side. They stay there when the cans are disassembled. The
> mobile charges are not *in* the dielectric but *on* it, and the dielectric
> is polarized as well.
>
>
>
>         -- Donald
>
> .....................................................................
> Donald E. Simanek
> dsimanek@eagle.lhup.edu                 http://www.lhup.edu/~dsimanek
> .....................................................................