How to Colonize an Asteroid
Whenever an electrical current flows through a wire, a magnetic field is created around the wire. This is referred to as an "electromagnetic field", or an "electrically induced magnetic field". {R.4.2.17} It is a temporary magnetism which will go away when the current stops flowing through the wire, although it can sometimes impart a semi-permanent magnetic charge to ferrous objects.
There is a very simple experiment you can do with a compass which will demonstrate the presence of the magnetic field around a current carrying wire.
© 1998, Robert Lyon Richards