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Re: There's work, and then there's work

one could imagine two identical capacitors with superconducting plate
and leads.
Charge one and then connect it in parallel with the other.
Calculate and account for the 'missing' electrostatic energy.






At 3:58 PM -0600 2/3/03, RAUBER, JOEL wrote:

However, one could, as a matter of a gedanken experiment imagine what would
happen if the battery could be made to be superconducting; i.e. "neglible
resistance". Nicht Wahr?

Joel R.

-----Original Message-----
From: Hugh Haskell [mailto:hhaskell@MINDSPRING.COM]
Sent: Monday, February 03, 2003 2:09 PM
To: PHYS-L@lists.nau.edu
Subject: Re: There's work, and then there's work


At 10:28 -0800 2/3/03, David Rutherford wrote:
>
>I don't know much about superconductivity, but shouldn't you be able
>charge the capacitor in the absence of resistance (superconducting
>circuit). Then, since the energy loss doesn't depend on R, you would
>still have to get 1/2 CV^2 for the energy stored on the
capacitor. But
>where does the other 1/2 CV^2 energy go, in this case? Or maybe the
>energy stored on the capacitor in the first place is
actually CV^2, not
>1/2 CV^2, even in the presence of nonzero R.
>
Even if you have superconducting wires and no resistor in the
circuit, we still, as far as I know, don't have superconducting
batteries. Every battery has an internal resistance, and in the
absence of resistance anywhere else in the circuit, the (CV^2)/2 that
is lost to the resistor, will be lost to the resistor in the battery.

Sorry, there ain't no free lunch.

Hugh
--

Hugh Haskell
<mailto:haskell@ncssm.edu>
<mailto:hhaskell@mindspring.com>

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