Question

what happens if the switches in figure A and B are turned ON?​

Answer 1

If the switches are turned on, then the following things will happen -

• Both the nails made of soft iron and steel, will become electromagnets when we will turn on the switches.
• We know that soft iron core has higher permeability than the steel core. So, the electromagnet with soft iron core will be stronger than the electromagnet with steel core.

But there will be a difference.

• After sometime, when we will turn off the switches, the soft iron nail will immediately (almost) loose its magnetism but the steel nail will retain the magnetism for some time.
• That's why, we use soft iron core in maximum cases, because immediate deactivation of magnetism is required in most cases.
• Also, the steel nail will be more difficult to magnetise than the soft iron nail, in the first hand.