Xref: utzoo sci.electronics:6403 sci.physics:8393
Path: utzoo!attcan!uunet!zephyr!tektronix!tekcrl!tekgvs!arnief
From: arnief@tekgvs.LABS.TEK.COM (Arnie Frisch)
Newsgroups: sci.electronics,sci.physics
Subject: Re: HV Cap Fun!
Summary: I  must have heard this first about 30 years ago......
Message-ID: <5255@tekgvs.LABS.TEK.COM>
Date: 1 Jun 89 15:40:07 GMT
References: <4924@m2c.M2C.ORG> <3806@mit-amt> <20772@quacky.mips.COM>
Followup-To: sci.electronics,sci.physics,poster
Organization: Tektronix Inc., Beaverton, Or.
Lines: 18

In article <20772@quacky.mips.COM>, vaso@mips.COM (Vaso Bovan) writes:
> A Paradox of Capacitor Energy Storage
> Consider an ideal 2uF (for computational ease) capacitor charged by a 10 volt 
> source. Eventually, the energy stored is (1/2)*CV^2=100 joules.
> 
> Consider the capacitor to be isolated from the voltage source, and then
> directly shorted across an identical (ideal) capacitor. Eventually, the
> voltage across each capacitor will be 5V. Now, there are two equally
> charged capacitors, each storing (1/2)*CV^2= 25 joules, for a total of
> of 50 joules.  What happened to the other 50 joules ?


In real circuits, infinite currents are not allowed - either the
inductance or resistance of the circuit prevents the current from
reaching infinite value.  In this circuit, no resistance is specified
and no inductance is specified, so I guess the current - on paper -
could be infinite for zero time (i.e. an impulse).  Just like I guess
the energy - on paper - gets radiated into free space.