The reason why a magnet has magnetic force is that the earth's magnetic field and current will continue to be strongly combined because of the rotation of the earth. Finally, the entire earth becomes a large magnetic field. Earth's minerals such as nickel, cobalt, and iron are rotated by the earth's rotation, and become natural magnets.
Everyone knows that there is a gravitational field between substances. Similar to a magnetic field, it is a field that covers the space around the magnetic pole. The size of the magnetic field can be expressed by the number of imaginary lines of magnetic force. The more dense the lines of magnetic force are, the stronger the magnetic field is, and the weaker the magnetic field is.