Is the Earths north pole a north or a south magnetic pole?
By definition, the tip of a compass which points toward the “north” pole of the earth is a magnetic north pole. Therefore, the north pole of the Earth is actually a south magnetic pole (unlike poles attract). Again: geographic north is a magnetic south; geographic south is a magnetic north. How long do magnets hold their magnetic strength? If the magnets are not subjected to external magnetic fields high enough to cause demagnetization – and/or – elevated temperatures above the advertised maximum use temperature the field will remain at or near as received. This could be expected last for the life of the application. What is a Helmholtz coil? Used in pairs, these are coils of wire connected to an integrating (totalizing) fluxmeter so that when a magnet is moved relative to the coils, the resulting current in the coils is measured and totalled. The magnet must be positioned properly, relative to the coils, and can be extracted from the pair of coils or rotated 90 degrees in the pair of
