Lost energy (Re: Van de Graaff /Pelletron (fwd)) (fwd)

[Steven Roys <sroys@xxxxxxxx>]

---------- Forwarded message ----------
Date: Mon, 19 Jan 2004 21:31:22 -0200
From: Antonio Carlos M. de Queiroz <acmq@xxxxxxxxxxxxxxxx>
To: High Voltage list <hvlist@xxxxxxxxxx>
Subject: Lost energy (Re: Van de Graaff /Pelletron (fwd))

High Voltage list wrote:

>         Here's another question whose answer should be obvious, but has puzzled
> lots of guys.  Suppose we take a capacitor charged to voltage V and
> connect it to an identical one with no charge.  The original energy was
> 1/2 CV^2.  Now we have two capacitors with voltage V/2, and each has an
> energy of 1/2 C(V/2)^2; the sum is CV^2/4, or half the starting energy.
> Question is "Where did the LOST energy go?".

Add a resistor in the connection and redo the calculations. The excess
of energy is dissipated in the resistor, and is always the same for
any resistance, even at the limit of zero resistance. But there is no
zero resistance.
Make a test with two large capacitors storing a few Joules and you will
see the energy being dissipated...

> P.S. Antonio does such beautiful work that I wish he'd make a pelletron
> in his spare time, post the pictures, and describe the results!!!!!

Some day. I would prefer a disk with sectors instead of a chain. It's
easier to make and can move at high speed easily.

Antonio Carlos M. de Queiroz