10 Jun
2009
10 Jun
'09
4:01 p.m.
On Jun 9, 2009, at 6:37 PM, Brent Hilpert wrote:
I don't claim to have a full physics understanding
of the issue but
I think a rough hand-waving explanation is that with the capacitor
charged and
the dielectric under potential stress, some charge creeps into and
is held by
the dielectric itself. It takes time for the charge to creep into the
dielectric. Once the potential is removed by shorting/loading the
cap, the
dielectric charge will redistribute itself to reflect the new
potential state,
i.e. creep back out, but this too takes time. If the discharge path
has been
removed the charge will accumulate on the plates.
Interesting. And bizarre.
Search for "dielectric absorption", or look
up "permittivity" in
Wikipedia to
get an idea of just how complex capacitors are (!)
Yes, I'm aware of their complexity...From my childhood days I
thought they were simple, but in recent years I've studied them
pretty closely. I've been dabbling in metrology for a few years now
and have become amazed at the complexity behind the "simple" things
that are the underpinnings of all things electronic. It's
fascinating. Anyone interested in electronics would do well to
investigate this a bit.
-Dave
--
Dave McGuire
Port Charlotte, FL