Re: power v energy measurements, was Re: SSTC does 10 foot sparks

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

Original poster: Mddeming-at-aol-dot-com 

Hi John, All,

My comments interspersed.

In a message dated 6/23/04 1:34:26 PM Eastern Daylight Time, 
tesla-at-pupman-dot-com writes:

 >The tests consist of finding the TC input energy by connecting a wattmeter
 >to the input of the TC. This will give you input watts per second (joules).

Watts per second is not Joules. Watt seconds is Watts TIMES seconds= 
Joules. Watts per second is Watts DIVIDED by Seconds.Watts per second is 
therefore Joules per second squared, or some sort of "acceleration of 
energy", or "velocity of power", or some such meaningless quantity.

 >You then turn up the Variac so you have 120 watt seconds input and adjust
 >the spark output for a continuous 120 sparks per second. You will then have
 >120 watt seconds / 120 sparks per second giving you  "one joule per spark"

Unfortunately, 120 watt seconds/120 sparks per second would be
  (120 W. sec) /120 spark/sec = 1 Watt sec^2

I think what you meant is
120 Watts / 120 sparks/Sec = (120 Joules/sec)/(120 sparks/sec) = 1 Joule/spark
which is dimensionally consistent.

Inverting this does give you sparks/joule. Assuming all sparks are the same 
size and that each spark contains energy from exactly one-half input cycle, 
your formula holds.

 >or "spark inches per joule of energy". I did this for my small TC and
 >obtained 8.25 inches per joule. If you perform this test with any small
 >SPTC or SSTC you will have a fair energy comparison of the Tesla coils.
 >Of course the 120 sparks per second would have to be changed to the actual
 >number per second.

I like your concept, and fortunately the mistakes in nomenclature and the 
mistakes in math exactly canceled out to give you the answer you seek, but 
I would hate for anyone with a shaky understanding of math and physics to 
have to follow the development. ;^)

Matt D.