Re: (Fwd) RE: Longitudinal Waves

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

Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-qwest-dot-net>" <evp-at-pacbell-dot-net>

Tesla list wrote:
> 
> Original poster: "David Thomson by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <dave-at-volantis-dot-org>
> 
> Hi Malcolm,
> 
> >Having spent half a lifetime repairing oscilloscopes as well as calibrating
> them I must strongly disagree with the statements in that paragraph. Bear in
> mind that you can invert one channel of most if not all scopes. The fact
> that there is no DC shift in a pure sinusoidal waveform when you do that
> speaks volumes.

	... and the zeroing adjustments are still set set correctly! 
 
> I've been looking for the reference that I derived my information from.  I
> cannot find it just yet.
> 
> The DC shift has been shown by some experimenters to exist.
> 
> The shift was explained just as I am presenting it, that there are two
> opposite polarity waves working together.

	That explanation is nonsensical.  What is it supposed to mean?

>  While we are on the topic, what is the current scientific explanation for
> the variation of voltage in a damped sine wave?  What force is believed to
> determine when the wave will reverse direction?  I could use a little
> education on the current theory if you would indulge me.  I believe this is
> useful information for Tesla coils in general.
> 
> Dave

	You use the term "wave" when I think you really mean voltage (or
current).  In the case of electrical circuits the reversal occurs
because of the exchange of energy between the inductor and the
capacitor.  When the voltage across a parallel LC circuit goes through
zero all of the energy which was stored in the charge on the capacitor a
quarter cycle earlier is stored in the magnetic field of the inductor,
and so on.  Damping is simply the manifestation of energy loss on each
cycle, and does not alter the fact that there is no DC component in the
resultant waveform.  The mathematical expressions involved have been
around since at least the middle of the 19th century and apply equally
to mechanical vibrations.

Ed