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



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>

(919) 467-7610

Never ask someone what computer they use. If they use a Mac, they
will tell you. If not, why embarrass them?
--Douglas Adams
******************************************************