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RE: LF: To Ponder over the weekend

To: [email protected]
Subject: RE: LF: To Ponder over the weekend
From: "Ashlock,William" <[email protected]>
Date: Fri, 8 Nov 2002 11:27:42 -0500
Reply-to: [email protected]
Sender: <[email protected]>
Jim,

I think there is a Lowfer-like solutin to this problem. Seems to me that if
everything is assumed to be 'ideal' or 'loss-free' including the wires,
there would still have to be a TX loop antenna formed by the connections. At
the instant of connection there would be radiation of 25uJ at a frequency
dependent on the capacitance and inductance of the components.
(See, there is no problem anyone can introduce that has no oportunity for me
to put in a plug for TX loop antennas! <G>)

Have a good, mind relaxing, weekend! Bill A


This simple puzzle caused more discussion in my office this morning than it
had any right to....

Here is another conundrum along similar lines - you have two identical,
loss-free 1uF capacitors, one is charged to 10V, the other is discharged.
You then connect the two in parallel so the total C is now 2uF - charge
will flow from the charged capacitor into the discharged capacitor.
Assuming charge Q is conserved, and that Q=CV, the voltage must now be 5V.
But the stored energy in a capacitor =1/2CV^2, so with the single charged
capacitor, the stored energy is 1/2 x 1u x 100 = 50uJ, while with both
capacitors in parallel it is only 1/2 x 2u x 25 = 25uJ. So where has the
other 25uJ gone?

Cheers, Jim Moritz
73 de M0BMU




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