iron core

An iron core is a piece of iron placed inside a coil of wire to make an electromagnet much stronger.

• When electric current flows through the coil, it produces a magnetic field. The iron core becomes magnetised by this field and adds its own magnetic effect.
• Iron is especially useful because it is a soft magnetic material: it becomes magnetic easily when current flows and loses most of its magnetism when the current is switched off.
• Think of the coil’s magnetic field as a group of people all facing one way. Inside the iron, tiny magnetic regions line up in the same direction, making the overall magnet much stronger.
• An iron nail can act as a simple iron core. A coil wrapped around a nail can lift more paper clips than the same coil without the nail.
• Iron cores are used in devices such as electric bells, relays, scrapyard lifting magnets, and speakers because their magnetism can be switched on and off.