NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Test your magnetic compass.
From: Alexandre Eremenko
Date: 2012 Nov 16, 18:20 -0500
From: Alexandre Eremenko
Date: 2012 Nov 16, 18:20 -0500
Bill, I don't really understand, why alternating current produces a constant magnetic field. Ken confirms this but does not explain. But this is a phenomenon which I noticed long ago and can even measure with my compass. It is about 10 degrees, close to a wall electric switch. There are also constant magnetic fields produced by nails in the studs of an American house. (And by iron rods inside the concrete of Soviet houses:-) And there is even a simple magnetic devise based on this, it is called the stud finder. But the field produced by AC wiring is stronger. Alex. On Fri, 16 Nov 2012, Ken Muldrew wrote: > > > On 2012-11-16, at 2:55 PM, Bill Morris wrote: > >> Can some physicist or power engineer explain how an alternating current can produce a constant magnetic field? Could corona discharge really account for the observation or must we postulate rusty joints in transmission towers acting as rectifiers? >> > AC power lines produce AC magnetic fields, but you have to be within about a meter of the line for the strength of the B field to equal that of the earth. DC power lines are becoming more popular due to advances in power engineering. Currently there are only about one or two hundred DC high voltage lines worldwide but this number will increase soon (at least power companies seem to be marketing the safety of DC lines pretty aggressively, and they do make sense for technologies such as wind power). > > Ken Muldrew. > > > > : http://fer3.com/arc/m2.aspx?i=121152 > > >