(a) Name a material of which permanent magnets are made?
(b) Which of the two is stronger: and electromagnet or a permanent magnet?

Explanation

Electromagnets are supposed to be temporary magnets. When current is flowing, magnetism is established, and as soon as the current is switched off, magnetism is lost. Coercive force of the material to be used as core of an electromagnet should be small. An example of such material is soft iron. On the other hand, for permanent magnets we need to ensure that the material should have high coercive force. Once magnetised then it should not be easy to demagnetise the substance. A large value of retentivity is always desired to make permanent magnets but we cannot compromise with coercive force, and it must be large.