| || ||Iron is a magnetic material. There are magnetic particles inside the iron. In soft iron, these particles will line up with an external magnetic field. In this way, the soft iron core behaves like a magnet itself. Once the external field is taken away, the core will return to normal. |
Imagine we put a piece of soft iron in the middle of a coil of copper wire. When we switch on the current, the coil becomes an electromagnet. But also, the soft iron core becomes a magnet. It will add to the strength of the electromagnet.
The effect of the soft iron core is much more than doubling the current or the number of turns.