Dear student An electromagnet is a temporary magnet produced by current flowing through a solenoid with soft iron core. The magnetic field remains only when the current is flowing, in absence of current it has no magnetic effect. Materials required to make electro magnet : soft iron, insulated coper wire battery we cannot use steel as core of electromagnet because steel does not lose magnetism when current is stopped and it becomes permanent magnet. That is why steel is not used in making electro magnet. Regards