Question

why the core of an Electromagnet should be soft iron and not a steel

Answer 1

The soft iron inside the coil makes the magnetic field stronger because it becomes a magnet itself when the current is flowing. Soft iron is used because it loses its magnetism as soon as the current stops flowing. Soft iron is said to form a temporary magnet. In this way, the electromagnet can be switched on and off by turning the electricity on and off.

Answer 2

because soft iron instantly reacts with current and give magnetic field and stops by off current but steel take time to stops