Question

How is magnetism of the earth generated?

Answer 1

Basically, the motion of the electrically conducting iron in the presence of the Earth's magnetic field induces electric currents. Those electric currents generate their own magnetic field, and as the result of this internal feedback, the process is self-sustaining so long as there is an energy source sufficient to maintain convection.

Answer 2

Earth behaves like a magnet scientists say because north pole of the earth is south in the bar magnet similarly sothpole to the north of the bar magnet