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# Re: VA and stored energy in capacitors

```Original poster: "Jolyon Vater Cox by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jolyon-at-vatercox.freeserve.co.uk>

Sorry if original text was confusing  -my email does not apparently support
Greek symbols.

"VA" is the apparent power of the capacitor in volt-amperes, "p" should
have been "pi" (3.1416), "F" is  the frequency in Hertz and "E" the energy
stored in the capacitor in Joules. The equation
VA =4 pi FE
relates power to stored energy in a capacitor in an AC circuit. Other
associated equations relate energy to power
(E =0.5CV^2 = VA/(4 pi F)) and frequency to power,(F = VA/(4 pi E)). In
hindsight, I realise these may not be appropriate to the current context.

So is power in a TC primary cap in fact given by equation VA=2FE, which is
the same as
VA= FCV^2?

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Thursday, May 30, 2002 3:00 PM
Subject: Re: VA and stored energy in capacitors

> Original poster: "harvey norris by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <harvich-at-yahoo-dot-com>
>
>
> --- Tesla list <tesla-at-pupman-dot-com> wrote:
> > Original poster: "Jolyon Vater Cox by way of Terry
> > Fritz <twftesla-at-qwest-dot-net>"
> > <jolyon-at-vatercox.freeserve.co.uk>
> >
> >
> > Since relationship between apparent power (VA),
> > frequency (F) and stored energy
> > (E) in a capacitor in an AC circuit is VA=4pFE,
> What does the 4p indicate? Dont know about the
> complications involved with an arc gap as you are
> asking, but I am confused here on your initial
> assessment. The cap energy storage is noted as .5CV^2,
> which tranfers twice per cycle, meaning that for 60
> hz, a 120 fold multiplication should give the energy
> transfer. Is your 4pF= 120? (for 60 hz)
> > where it is assumed that F is
> > the line frequency (50 to 60 Hz) during the period
> > when the capacitor is being
> > charged by the transformer prior to the firing of
> > the spark-gap, doesn't the
> > same equation apply when the gap fires when F
> > becomes the resonant frequency of
> > the Tesla coil primary?
> >
> > Does this not go some way into accounting for high
> > peak powers observed in TC
> > discharges?
> >
> >
> >
>
>
>

```