Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: How many joules --> e.m. waves?



At 05:46 AM 4/15/97 EDT, LUDWIK KOWALSKI wrote:
... the emission of e.m. waves is contradicted by the
common "discharge current" formula:

i=(V/R)*exp(-t/RC) where V is the initial d.o.p.

To show the conflict calculate the amount of heat, H, produced during the
discharge (an integral of i^2*R*dt from zero to infinity); the result is
H=0.5*C*V^2. In other words, FOR ANY FINITE R, the amount of heat is equal
to the initial electrostatic energy. No energy is left for the e.m. waves!
But sparking capacitors do emit waves. This is a reminder that the above
formula is only an approximation; it is not valid for very small RC (fast
discharging).
...
Ludwik Kowalski

Ludwik continues to inhabit models that are inductanceless and wonders why
they do not model observed behavior?
Let me do much the same.
It is not a question of the damping of a tuned circuit.
One can observe a radiated 'click' merely by switching off a steady current
through
a resistor from a battery.
There is a fourier analysis that shows the collection of harmonics
available from
such a square wave signal. Isn't that enough?

Regards
brian whatcott <inet@intellisys.net>
Altus OK