Re: general cap questions

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Crow Leader by way of Terry Fritz <twftesla-at-qwest-dot-net>" <tesla-at-lists.symmetric-dot-net>

A Farad is the unit of capacitance. It is one coulomb per volt. A coulomb
being a measure of charge (current time time). A coulomb is 1 amp second.

So, if we take a 1 farad cap and charge it to say 5 volts, it will store 5
coulombs of charge. The same cap will store only 1 coulomb of charge if
charged to 1 volt. In either case the energy storage of a capacitor is 1/2
voltage squared times capacitance. The assumed units are farads and energy
is in Joules. You can see that if you double the voltage in a capacitor you
do two things- you well, double the voltage it is storing, and you also
double the charge it can hold. Doubling the voltage across a cap will
increase energy storage by a factor of 4. 2x voltage times 2x charge = 4
times the energy.

You will rarely come across a 1 Farad capacitor. more usual values are in uF
nF or pF.

Voltage ratings are determined by the design and construction of the
capacitor itself. The same is true for the capacitance itself.

KEN



----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Friday, October 18, 2002 5:04 PM
Subject: general cap questions


> Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<Beans45601-at-aol-dot-com>
>
> What are farads? I know that they are a measure of capacitance, but what
does
> that mean? Is that how often they discharge, how much voltage they can
take, or
> what?
> Thanks
> Adam
>
>
>