Return-Path: Received: (qmail 12837 invoked from network); 8 Nov 2002 17:11:56 -0000 Received: from marstons.services.quay.plus.net (212.159.14.223) by mailstore with SMTP; 8 Nov 2002 17:11:56 -0000 Received: (qmail 7315 invoked by uid 10001); 8 Nov 2002 17:11:36 -0000 Received: from post.thorcom.com (193.82.116.70) by marstons.services.quay.plus.net with SMTP; 8 Nov 2002 17:11:36 -0000 Received: from majordom by post.thorcom.com with local (Exim 4.10) id 18ACes-0004r6-00 for rsgb_lf_group-outgoing@blacksheep.org; Fri, 08 Nov 2002 17:11:02 +0000 Received: from [212.1.130.1] (helo=smtp-1.visp.telinco.net) by post.thorcom.com with esmtp (Exim 4.10) id 18ACes-0004qx-00 for rsgb_lf_group@blacksheep.org; Fri, 08 Nov 2002 17:11:02 +0000 Received: from [212.1.153.222] (helo=pcuser) by smtp-1.visp.telinco.net with smtp (Exim 3.32 #1) id 18ACYR-0005Wd-00 for rsgb_lf_group@blacksheep.org; Fri, 08 Nov 2002 17:04:24 +0000 Message-ID: <002101c28749$d070a200$de9901d4@pcuser> From: "Hugh Burnham" To: rsgb_lf_group@blacksheep.org References: <01C28737.29992A90.g4jnt@thersgb.net> Date: Fri, 8 Nov 2002 17:10:11 -0000 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.00.2919.6600 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Subject: Re: LF: To Ponder over the weekend ... LF Activity ? Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: 8bit X-Spam-Status: No, hits=0.1 required=5.0tests=DEAR_SOMEBODY,QUOTED_EMAIL_TEXT,REFERENCES, SPAM_PHRASE_03_05,USER_AGENT_OEversion=2.42 Sender: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sorry to disillusion you academics, but it is in Nelcon and Parker, the standard A level Physics Text book when I was at school - I have it here - P.684 ! However I would add that if you increase the values, say to 100 Volts, and 10,000uF it is very clear what happens to the extra energy when you connect the terminals ... "SPLAT !" is a good onomatopoeic term. Is anybody going to be transmitting over the weekend ? When might I hear some signals on 73 / 136 ? 73 Hugh M0WYE ----- Original Message ----- From: "Andy talbot" To: Sent: Friday, November 08, 2002 2:57 PM Subject: RE: LF: To Ponder over the weekend > Can tell you come from a university background Jim, do you ask that of > applicants for courses at herts.ac? > I was asked exactly the same question when applying for Southampton Uni. in > 1976. > > Andy G4JNT > > -----Original Message----- > From: James Moritz [SMTP:j.r.moritz@herts.ac.uk] > Sent: 2002/11/08 11:52 > To: rsgb_lf_group@blacksheep.org > Subject: Re: LF: To Ponder over the weekend > > Dear Andy, LF group, > > At 09:38 08/11/2002 +0000, you wrote: > >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 > > > >