is the magnetic field?
Magnets attract iron. They attract or repel each other. Every magnet
is believed to have the so-called magnetic field around it, which
is invisible. Due to the influence of this magnetic field, magnets
attract or repel each other. The Earth also has its own magnetic
field. Even a piece of iron comes to have a magnetic field after
attracted by a magnet, which is not so strong as those of magnets.
Other than magnets, electric wires or power cables sometimes have
magnetic fields. However, this does not mean that they have their
own magnetic fields. They come to have magnetic fields only when
electric currents are passing through them: that is, electric currents
generate magnetic fields. (Magnets continue to have magnetic fields
almost permanently. There is no moment for them to lose their magnetic