Short Note On Magnetic Field Of Earth

A freely suspended magnet always points in the north-south direction even in the absence of any other magnet. This is due to the fact that the earth itself behave like a magnet which causes a freely suspended magnet (or magnetic needle) to point always in north and south direction. 

The shape of the earth’s magnetic field resembles that of an imaginary bar magnet of length one fifth of earth’s

diameter buried at its center. The south pole of earth’s magnet is in the

geographical north because it attracts the north pole of the suspended magnet. 

Similarly, the north pole of earth’s magnet is in the geographical south. The axis of earth's magnet and the geographical axis do not coincide with each other. 

The axis of earth’s magnetic field is inclined at an angle of about 15° degree with the geographical axis. Due to

this a freely suspended magnet makes angle of about 15° degree with the geographical axis and points only approximately in the north-south

directions at a place.

or A freely suspended magnet

does not show exact geographical north and south because the magnetic axis and geographical axis of the earth do not coincide. 

The earth’s magnetism is due to the magnetic effect of current which is flowing in the liquid-core at the center of the earth.