X-Authentication-Warning: delorie.com: mail set sender to geda-user-bounces using -f X-Recipient: geda-user AT delorie DOT com Message-ID: <4F634F97.1060907@keensupport.net> Date: Fri, 16 Mar 2012 07:35:03 -0700 From: Joe Knapp Organization: Keen Support Services, LLC User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.2) Gecko/20120216 Thunderbird/10.0.2 MIME-Version: 1.0 To: geda-user AT delorie DOT com CC: Rob Butts Subject: Re: [geda-user] Daughter's Science Fair References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Reply-To: geda-user AT delorie DOT com Rob, You mention parallel and adjacent and that go me thinking about my motors and transformers classes. I think what you may need to acquaint yourself with is the concept of magnetic flux density. Here is a good illustration of you electromagnet: http://www.ndt-ed.org/EducationResources/CommunityCollege/MagParticle/Graphics/coil1.gif The blues lines represent the lines of magnetic flux, the denser the lines the stronger the magnetic force. You may notice that only two lines are drawn as circles, actually all the flux lines make circles, but illustrating them would make the illustration look like a toroid and less clear. None the less, you can see that the magnetic forces are concentrated in the center (i.e. in your nail) and expand when they leave your coil and reconnect with the opposite polarity. Finally, the flux density is highest at the end of your nail and not the sides. Good Luck, Joe On 03/16/2012 07:02 AM, Rob Butts wrote: > My nine-year-old daughter has a science fair tomorrow. We are doing > simple electromagnets out of nails. We are just using one C battery > with approximately a 30-penny nail and 26 guage wire wrapped around > the nail for two layers. When the battery is connected the nail has a > good magnetic strength in that it will pick up another nail not just > paper clips. > > I was thinking about showing how a current in one coil will induce a > current in another (how an electric toothbrush charges). We rigged up > another nail the same way but with a little bulb attached. Check my > theory, shouldn't the electromagnetic field produced by the coil and > nail with the battery induce a current in the other coil when placing > the nails adjacent and parallel? -- Keen Support Services, LLC http://keensupport.net