Return-Path: Received: (qmail 31760 invoked from network); 11 Nov 2002 11:56:21 -0000 Received: from warrior.services.quay.plus.net (212.159.14.227) by mailstore with SMTP; 11 Nov 2002 11:56:21 -0000 Received: (qmail 29705 invoked from network); 11 Nov 2002 10:55:39 -0000 X-Priority: 3 X-MSMail-Priority: Normal Received: from post.thorcom.com (193.82.116.70) by warrior.services.quay.plus.net with SMTP; 11 Nov 2002 10:55:39 -0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-SQ: A Received: from majordom by post.thorcom.com with local (Exim 4.10) id 18BCDC-0005d0-00 for rsgb_lf_group-outgoing@blacksheep.org; Mon, 11 Nov 2002 10:54:34 +0000 Received: from [194.73.73.116] (helo=lutetium) by post.thorcom.com with esmtp (Exim 4.10) id 18BCDC-0005cr-00 for rsgb_lf_group@blacksheep.org; Mon, 11 Nov 2002 10:54:34 +0000 Received: from host213-122-12-159.in-addr.btopenworld.com ([213.122.12.159] helo=there) by lutetium with smtp (Exim 3.22 #15) id 18BCDB-0002zB-00 for rsgb_lf_group@blacksheep.org; Mon, 11 Nov 2002 10:54:33 +0000 From: "Steve Thompson" To: rsgb_lf_group@blacksheep.org Date: Mon, 11 Nov 2002 10:55:57 +0000 X-Mailer: KMail [version 1.3.1] References: <7D653C9C42F5D411A27C00508BF8803DCB9CCB@mail.dstl.gov.uk> In-reply-to: <7D653C9C42F5D411A27C00508BF8803DCB9CCB@mail.dstl.gov.uk> MIME-Version: 1.0 Message-ID: Content-Type: text/plain; charset=iso-8859-1; format=flowed Subject: LF: An answer to Monday's puzzle Content-Transfer-Encoding: 8bit X-Spam-Status: No, hits=-2.0 required=5.0tests=IN_REP_TO,QUOTED_EMAIL_TEXT,REFERENCES,SPAM_PHRASE_00_01, SUBJECT_FREQversion=2.42 Sender: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group On Monday 11 November 2002 08:46, you wrote: > You have a small box whose internal workings you can't see, but the box > has two terminals. You measure these two terminals with a voltmeter, and > it measures precisely 1V. You short the two terminals with an ammeter, > and it reads precisely 1A. You then conclude the internal circuit is > either a Thevenin source (an ideal 1V voltage source with a 1-ohm series > resistor) or a Norton source (an ideal 1A current source with a 1-ohm > shunt resistor). Using standard laboratory equipment, how could you > determine which one it is. I'm feeling pleased with myself - I honestly worked this out from scratch! Apply a 1V external source and measure the current. Steve