Electromagnets (Oxford AQA IGCSE Physics): Revision Note

Electromagnets

• A solenoid can be used as an electromagnet by adding a soft iron core

• The iron core will become an induced magnet when current is flowing through the coils 

  • The magnetic field produced by the solenoid and the iron core will create a much stronger magnet overall

• The magnetic field produced by the electromagnet can be switched on and off

  • When the current is flowing there will be a magnetic field produced around the electromagnet

  • When the current is switched off there will be no magnetic field produced around the electromagnet

Electromagnet diagram

• Changing the direction of the current also changes the direction of the magnetic field produced by the iron core

Factors affecting magnetic field strength

• The strength of the magnetic field produced around a solenoid can be increased by:

  • Increasing the size of the current which is flowing through the wire

  • Increasing the number of coils in a given length of wire

  • Maintaining the number of turns and reducing the length of the wire

  • Adding an iron core through the centre of the coils

• The strength of an electromagnet can be changed by:

  • Increasing the current to increase the magnetic field produced around the electromagnet

  • Decreasing the current to decrease the magnetic field produced around the electromagnet