Magnetic materials are classified as either magnetically hard or magnetically soft. Magnetically soft materials are easily magnetised, but the induced magnetism is usually transient. If you rub a permanent magnet along a nail or a screwdriver, the nail or screwdriver will become temporarily magnetised and emit their own weak magnetic field. This is because the external magnetic field temporarily aligns a large number of their iron atoms in the same direction.
Magnetic Materials hard materials, like magnetically soft materials, can be magnetised by a strong external magnetic field, such as that produced by an electromagnet. The difference is that magnetically hard materials will remain magnetised indefinitely unless demagnetized by an opposing magnetic field, heated above their curie temperature, or cooled.
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