The magnitude of the earth magnetic field at its surface ranges from 25 to 65 microteslas (0.25 to 0.65 gauss).



On Earth, flowing of liquid metal in the outer core of the planet generates electric currents. The rotation of the earth on its axis causes these electric currents to form a magnetic field which extends around the planet. The magnetic field is extremely important to sustaining life on earth.


What would happen if the earths magnetic field disappeared? 
if the magnetic field weakens enough or temporarily disappears during the flip, then the earth could be hit with dangerous amounts of solar radiation and cosmic rays. The exposure could mean that more people develop cancer, Renne said, though there's no scientific proof this could happen.


how do we use the magnetic field?
Birds use earth magnetic fields sort of a heads-up display to help them navigate the globe. The earth magnetic field is a result of the movement or convection of liquid iron in the outer core. As the liquid metal in the outer core moves, it generates electric currents, which lead to a magnetic field.


earth magnetic field is, contrary to popular belief, is extremely weak, many times weaker than even a common Ferro-ceramic bar magnet. It's a strength at earth surface is roughly 25-65 microteslas, or 0.25-0.65 gauss, whereas a small bar magnet is around 10,000 microteslas or 100 gausses.


computer simulation of the earth field in a period of normal polarity between reversals. The lines represent magnetic field lines, blue when the field points towards the center and yellow when away. The rotation axis of the Earth is centered and vertical. The dense clusters of lines are in the earth core.


while the north and south magnetic poles are usually located near the geographic poles, they slowly and continuously move over geological time scales, but sufficiently slowly for ordinary compasses to remain useful for navigation. the earth fields reverse and the north and south magnetic poles respectively, abruptly switch places. These reversals of the geomagnetic poles leave a record in rocks that are values to paleomagnetists in calculating geomagnetic fields, in the past such information, in turn, is helpful in studying the motions of continents  and ocean floors in the process of plate tectonics