Re: A few Q's

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

Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz <twftesla-at-qwest-dot-net>" <acmq-at-compuland-dot-com.br>

Tesla list wrote:
> 
> Original poster: "Steve Greenfield by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <alienrelics-at-yahoo-dot-com>

> I thought it was the point at which the peak reached 0.707 of the
> original amplitude. That sticks in my head, maybe that was a rule
> of thumb for something else.

Relations with this 1/sqrt(2) terms appear everywhere. In this case,
if you force a resonant system with a sinusoidal source, you can first
find the frequency that causes maximum amplitude oscillations (w0),
and then search for the two frequencies, one above (w2) and one
below (w1) where the amplitude of the oscillations drop by the
factor 0.707. Q is then w0/(w2-w1). 

Antonio Carlos M. de Queiroz