Electromagnets (Edexcel IGCSE Physics): Revision Note

Electromagnets

• When an electric current flows in a wire it creates a magnetic field around the wire

• By winding the wire into a coil we can strengthen the magnetic field by concentrating the field lines

• If this wire is wound around a soft magnet, such as an iron, then an electromagnet is made (see the electromagnet diagram below)

  • The electromagnet is magnetic only when current flows through the wire

Electromagnet diagram

Electromagnets are made up of a coil of wire wrapped around an iron core

• The strength of an electromagnet’s magnetic field may be increased by:

  • Increasing the current in the coil

  • Adding more turns to the coil

• The magnetic field around an electromagnet has the same shape as the one around a bar magnet

• The field can be reversed by reversing the direction of the current

  • However, bar magnets are always magnetic, unlike electromagnets