8.4 Temporary and Permanent Magnets
Temporary magnets are magnets that work in the presence of a magnetic field of permanent magnets. Once the magnetic field vanishes, they lose their magnetic properties. Usually, soft iron is used to make temporary magnets. Paper clips, office pins, and iron nails can easily be made into temporary magnets. Electromagnets are also good examples of temporary magnets.
Permanent magnets retain their magnetic properties forever. These are either found in nature or artificially made by placing objects made of steel and some special alloys in a strong magnetic field for a sufficient time. There are many types of permanent magnetic materials, for example, cobalt, alnico, and ferrite.
A simple activity can demonstrate the difference: a chain of iron nails hanging from a magnet collapses immediately when removed from the magnet, whereas a chain of steel nails remains attached to each other for some time. This shows that the magnetism induced in the iron nails is temporary, while that in the steel nails is permanent.