Editing Magnet (section)

=== Polarity ===

The north pole of a magnet is defined as the pole that, when the magnet is freely suspended, points towards the Earth's [[North Magnetic Pole]] in the Arctic (the magnetic and [[Geographical pole|geographic poles]] do not coincide, see [[magnetic declination]]). Since opposite poles (north and south) attract, the North Magnetic Pole is actually the ''south'' pole of the Earth's magnetic field.<ref>{{cite book | last = Serway | first = Raymond A. | author2 = Chris Vuille | title = Essentials of college physics | publisher = Cengage Learning | year = 2006 | location = USA | page = 493 | url = https://books.google.com/books?id=8n4NCyRgUMEC&pg=PA493 | isbn = 0-495-10619-4 | url-status = live | archive-url = https://web.archive.org/web/20130604005509/http://books.google.com/books?id=8n4NCyRgUMEC&pg=PA493 | archive-date = 2013-06-04 }}</ref><ref>{{cite book | last = Emiliani | first = Cesare | title = Planet Earth: Cosmology, Geology, and the Evolution of Life and Environment | publisher = Cambridge University Press | year = 1992 | location = UK | page = 228 | url = https://books.google.com/books?id=MfAGpVq8gpQC&pg=PA228 | isbn = 0-521-40949-7 | url-status = live | archive-url = https://web.archive.org/web/20161224181416/https://books.google.com/books?id=MfAGpVq8gpQC&pg=PA228 | archive-date = 2016-12-24 }}</ref><ref>{{cite book | last = Manners | first = Joy | title = Static Fields and Potentials | publisher = CRC Press | year = 2000 | location = USA | page = 148 | url = https://books.google.com/books?id=vJyqbRPsXYQC&pg=PA148 | isbn = 0-7503-0718-8 | url-status = live | archive-url = https://web.archive.org/web/20161224182401/https://books.google.com/books?id=vJyqbRPsXYQC&pg=PA148 | archive-date = 2016-12-24 }}</ref><ref name="Hyperphysics">{{cite web | last = Nave | first = Carl R. | title = Bar Magnet | work = Hyperphysics | publisher = Dept. of Physics and Astronomy, Georgia State Univ. | year = 2010 | url = http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html | access-date = 2011-04-10 | url-status = live | archive-url = https://web.archive.org/web/20110408200208/http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html | archive-date = 2011-04-08 }}</ref> As a practical matter, to tell which [[wikt:magnetic pole|pole]] of a magnet is north and which is south, it is not necessary to use the Earth's magnetic field at all. For example, one method would be to compare it to an [[electromagnet]], whose poles can be identified by the [[right-hand rule]]. The magnetic field lines of a magnet are considered by convention to emerge from the magnet's north pole and reenter at the south pole.<ref name="Hyperphysics" />