Q.Electromagnets are made of soft iron because soft iron has

Electromagnets need a core that magnetises strongly under current but loses its magnetism the instant the current is switched off — that means low retentivity and low coercivity, which is exactly soft iron's property (unlike steel, used for permanent magnets).

Retentivity is the residual magnetism a material retains after the magnetising field is removed. Coercivity is the reverse field needed to bring that residual magnetism to zero.

An electromagnet must become strongly magnetic only while current flows, and must lose its magnetism as soon as the current is switched off (so it can be turned on/off like a switch, as in relays, electric bells, cranes, etc.). This requires:

• Low retentivity: doesn't stay magnetised once the field is removed. …