Return-Path: Received: (qmail 27790 invoked from network); 8 Nov 2002 13:25:09 -0000 Received: from warrior.services.quay.plus.net (212.159.14.227) by mailstore with SMTP; 8 Nov 2002 13:25:09 -0000 Received: (qmail 22958 invoked from network); 8 Nov 2002 12:36:56 -0000 Received: from post.thorcom.com (193.82.116.70) by warrior.services.quay.plus.net with SMTP; 8 Nov 2002 12:36:55 -0000 X-Priority: 3 X-MSMail-Priority: Normal X-SQ: A Received: from majordom by post.thorcom.com with local (Exim 4.10) id 18A8Mt-0003rg-00 for rsgb_lf_group-outgoing@blacksheep.org; Fri, 08 Nov 2002 12:36:11 +0000 Received: from [193.212.240.200] (helo=virus-out.ttyl.com) by post.thorcom.com with esmtp (Exim 4.10) id 18A8Ms-0003rC-00 for rsgb_lf_group@blacksheep.org; Fri, 08 Nov 2002 12:36:10 +0000 Received: from [134.47.162.190] by virusscan.ttyl.com with ESMTP for rsgb_lf_group@blacksheep.org; Fri, 8 Nov 2002 13:35:39 +0100 Received: from tns-fbu-22-215.corp.telenor.no ([134.47.162.192]) by tns-fbu-22-209.corp.telenor.no with Microsoft SMTPSVC(5.0.2195.4453); Fri, 8 Nov 2002 13:35:38 +0100 Received: from tns-fbu-22-213.corp.telenor.no ([134.47.162.191]) by tns-fbu-22-215.corp.telenor.no with Microsoft SMTPSVC(5.0.2195.4453); Fri, 8 Nov 2002 13:35:37 +0100 Received: from TNS-FBU-2E-003.corp.telenor.no ([134.47.164.201]) by tns-fbu-22-213.corp.telenor.no with Microsoft SMTPSVC(5.0.2195.4453); Fri, 8 Nov 2002 13:35:37 +0100 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 content-class: urn:content-classes:message MIME-Version: 1.0 Date: Fri, 8 Nov 2002 13:35:37 +0100 Message-ID: <2D280BB697C7EE4C979C5C89925418EF368F75@TNS-FBU-2E-003.corp.telenor.no> Thread-Topic: LF: To Ponder over the weekend Thread-Index: AcKHIBCZz8ZXxkSWR1iLAAfF89YO6wAAx1Iw From: jan-martin.noding@telenor.com To: rsgb_lf_group@blacksheep.org X-OriginalArrivalTime: 08 Nov 2002 12:35:37.0762 (UTC) FILETIME=[57463820:01C28723] Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: 8bit Subject: SV: LF: To Ponder over the weekend X-Spam-Status: No, hits=2.2 required=5.0tests=DEAR_SOMEBODY,NO_REAL_NAME,SPAM_PHRASE_00_01version=2.42 X-Spam-Level: ** Sender: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group ha ha Yes, you said 25µJ per capacitor..... 73 Jan-Martin, LA8AK -----Opprinnelig melding----- Fra: James Moritz [mailto:j.r.moritz@herts.ac.uk] Sendt: 8. november 2002 12:52 Til: rsgb_lf_group@blacksheep.org Emne: 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