We know that, a magnet is an object that produces a magnetic field. This may be an electromagnet or a permanent magnet. The former is made from a coil of wire that acts as a magnet when an electric current passes through it. The magnetic effect stops when one switches off the current. The latter does not need any external source of electric current, and once being magnetized, it creates its own persistent magnetic field. Here, it is interesting to note that an electromagnet can be described in the framework of classical Maxwell equations, while for permanent magnets, one has to resort to quantum mechanics. The point is that magnetization of a permanent magnet is directly caused by the magnetic moments of, say, electrons with spin \(s=\hbar /2\) , such that the total magnetization is proportional to the vector sum of spins. For example, \(^{26}Fe\) has four unpaired electrons in its \(n=3\) shell.