At Cambridge, Massachusetts the magnitude of the earth's field is about 5.8 x 10 -5 T and has an angle of dip that was 73 degrees. 5.8 x 10 -5 T Worldbook Encyclopedia, vol. T Magnetic forces are produced by the motion of charged particles such as electrons, indicating the close relationship between electricity and magnetism.
Polarized magnets have north seeking and south seeking poles.
Like poles repel one another and unlike poles attract. A magnetic field is a detectable force that exists at every point in the region around the magnet or electric current. Magnetic fields are usually represented by flux lines. At any point the direction of the magnetic field is proportional to the space between the flux lines. Where flux lines are farther apart the magnetic field is weaker.