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, 22:10 -0500
From: Alexandre Eremenko
Date: 2012 Nov 16, 22:10 -0500
Bill, > Power lines almost always carry alternating current > and so could be expected to have a magnetic field alternating > at 50 or 60 Hz and I would not expect an effect on a magnetic compass. That power lines in MY appartment have an effect is an experimental fact, of which I have no explanation:-) In the immediate vicinity. > Like Byron, I believed that magnetic force between two > magnets varies inversely as the square of the distance between them, but > the Admiralty Manual of Navigation 1970 (B.R.45 (1) states that "...the > field strength due to a short magnet varies inversely as the cube of the > distance from the magnet..." Admiralty manual is right:-) See for example, "Magnetic dipole" on Wikipedia. This explains, by the way, the fact which puzzled me a lot in my childhood: how can steel ships use magnetic compass ? Alex.