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

  A) coil

  B) iron core

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

  1. Increasing the current in the coil
  2. 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