LF: Re: Re: To Ponder over the weekend

["Johan Bodin" <sm6lkm.jbeab@swipnet.se>]

g6tmk wrote:

> My guess is the 10uF capacitor becomes 1uF and the voltage rises to 100V.
That's my guess too, but... W [stored energy] = V^2*C / 2:

With oil: V=10V, C=10u => W = 10*10*10u / 2 = 500 uJ
Without oil: V=100V, C=1u => W = 100*100*1u / 2 = 5000 uJ

Assuming that no charge goes away with the oil, the stored energy
will increase by a factor of ten. Hmm... Force * distance = energy.
When gravity pulls the oil away from the plates, the oil has to fight
against an electrostatic force thereby injecting energy into the
capacitor, I guess...

Will a charged air variable capacitor try to turn itself towards
the maximum setting? :-)

73
Johan SM6LKM