Why earth act like a bar magnet ?
Answers
Answer:
Earth's magnetic field is caused by a dynamo effect. On Earth, flowing of liquid metal in the outer core of the planet generates electric currents. The rotation of Earth on its axis causes these electric currents to form a magnetic field which extends around the planet.
Answer:
The Earth act like a bar magnet because
the Earth is a magnet. It is not a permanent magnet, but an electromagnet.
Deep in the Earth, molten metal flows due to heat which causes convection. This flow tends to organize itself into patterns, just like the patterns you'll see in oil if you heat it in a frying pan.
Such patterns in a flowing conductor tend to create magnetism.
The same idea is used in the "dynamo", a
device that creates both electric current
and magnetism from moving conductors.
Commercial dynamos are the source of essentially all of our wall-outlet electricity.
The principle of a dynamo is this: if there is a little magnetic field, then when a conductor moves past it, it causes current to flow.
That current creates a magnetic field which, if the geometry is right, enhances the original field.
So it grows until the force is large enough to modify the pattern and this pattern is the magnetic field of the earth.