http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
1 online resource (streaming video file)
No matter how many times you break a magnet apart, each piece has a north and south pole. Why? Search for the origin of magnetism and learn how magnetic field lines differ from those of an electric field, and why Earth has a magnetic field.
Features: Richard Wolfson Ph.D., Dartmouth College
Originally produced by The Teaching Company/The Great Courses in 2011.