Xref: utzoo sci.physics:3497 sci.electronics:3008
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From: leonard@bucket.UUCP (Leonard Erickson)
Newsgroups: sci.physics,sci.electronics
Subject: Re: capacitors
Keywords: electromagnetism, capacitors, circuits
Message-ID: <898@bucket.UUCP>
Date: 25 May 88 09:34:18 GMT
References: <2992@phoenix.Princeton.EDU>
Reply-To: leonard@bucket.UUCP (Leonard Erickson)
Organization: Rick's Home Grown Unix; Portland, OR
Lines: 30

In article <2992@phoenix.Princeton.EDU> tycchow@phoenix.Princeton.EDU (Timothy Yi-chung Chow) writes:
<The following problem appears in many books on elementary physics,
<elementary electromagnetism, and elementary circuit theory:
<
<Two capacitors, with capacitances C1 and C2 respectively, carry
<charges Q1 and Q2 respectively.  Find the total energy stored.
<Now connect the positive plates and connect the negative plates.
<Show that the total energy stored decreases.  Where has the
<energy gone? 
<
<The energy calculations are trivial.  What intrigues me is the
<question of the lost energy.  The answer usually given is that
<a current flows when the capacitors are connected, and this
<causes energy to be dissipated as heat.  However, suppose we
<idealize the problem and assume zero resistance.  Surely energy
<is still lost somehow.  How do we explain this?

The only time I came across this problem was in an old physics book
dug out of a storeroom when I was in high school. The text explicitly
stated that the energy was lost as electromagnetic radiation and
gave formulas for calculating the frequency(!). I lost my copies
of these and many other interesting formulas when my briefcase was
stolen late in my junior year :-(


-- 
Leonard Erickson		...!tektronix!reed!percival!bucket!leonard
CIS: [70465,203]
"I used to be a hacker. Now I'm a 'microcomputer specialist'.
You know... I'd rather be a hacker."