electromagnet

An electromagnet is a magnet made by passing electric current through a coil of wire, usually wrapped around a piece of iron.

• The electric current creates a magnetic field around the coil. The iron core becomes magnetised and makes the electromagnet much stronger.
• Unlike a permanent magnet, it can be switched on and off. When the current stops, the iron usually loses most of its magnetism.
• Its strength can be controlled: increasing the current or winding more turns of wire around the iron core makes it able to lift more iron objects.
• Its poles can also be changed. Reversing the direction of current swaps the North and South poles, like turning a magnet around without moving it.
• Electromagnets are useful in devices that need controllable magnetism, such as electric bells, loudspeakers, relays, and cranes that lift scrap iron and then release it safely.

An electromagnet is like a magnet with a switch: electricity lets us decide when it attracts objects and how strongly it does so.