Electromagnetism

Section 1Current and magnetic fields

When an electric current flows through a wire, it produces a magnetic field around the wire. This shows that electricity and magnetism are connected.

Section 2Solenoids

A solenoid is a coil of wire. When current flows through it, the magnetic field becomes stronger and more like the field around a bar magnet. The field is strongest inside the coil.

Section 3Electromagnets

An electromagnet is made by wrapping insulated wire around a soft iron core and passing current through the wire. It is temporary because it can be switched on and off.

Section 4Increasing strength

An electromagnet can be made stronger by increasing the current, adding more turns of wire, or using a soft iron core. These changes make the magnetic effect stronger.

Section 5Uses of electromagnets

Electromagnets are used in electric bells, relays, loudspeakers, scrap-yard cranes, and some motors. A crane can pick up metal when current flows and release it when the current is switched off.