This "field regeneration" takes place because magnetic field lines are trapped in good electrical conductors, such as the molten iron of the Earth's outer core.
(This "field regeneration; takes; place; because magnetic field lines are trapped in good electrical conductors, such as the molten iron of the Earth's outer core) (magnetic field lines; are trapped; in good electrical conductors, such as the molten iron of the Earth's outer core)
This "field regeneration magnetic field lines
takes are trapped
place because magnetic field lines are trapped in good electrical conductors, such as the molten iron of the Earth's outer core
in good electrical conductors, such as the molten iron of the Earth's outer core