Permanent and Induced Magnets

Magnets produce magnetic fields

  • All magnets have two poles-north and south
  • All magnets produce a magnetic field, a region where other magnets or magnetic materials experience a force.(This is a non contact force-similar to the force on charges in an electric field)
  • You can show a magnetic field by drawing magnetic field lines
  • The lines always go from north to south and they show which way a force would act on a north pole if it was put at that point in the field
  • The closer together the lines are. the stronger the magnetic field. The further away from a magnet you get, the weaker the field is
  • The magnetic field is strongest at the poles of a magnet. This means that the magnetic forces are also strongest at the poles
  • The force between a magnet and a magnetic material is always attractive, no matter the pole
  • If two poles of a magnet are put near each other, they will each exert a force on each other. This force can be attractive or repulsive. Two poles that are the same(these are called like poles) will repel each other. Two unlike poles will attract each other.

Compasses show the directions of magnetic fields

  • Inside a compass is a tiny bar magnet. The north pole of this magnet is attracted to the south pole of any other magnet it is near. So the compass points in the direction of the magnetic field it is in
  • You can move a compass around a magnet and trace its position on some paper to build up a picture of what the magnetic field looks like
  • When they’re not near a magnet, compasses always point north. This is because the Earth generates its own magnetic field, which shows the inside(core) of the Earth must be magnetic

Magnets can be permanent or induced

  • There are two types of magnet-permanent magnets and induced magnets
  • Permanent magnets produce their own magnetic field
  • Induced magnets are magnetic materials that turn into a magnet when they’re put into a magnetic field
  • The force between permanent and induced magnets is always attractive
  • When you take away the magnetic field, induced magnets quickly lose their magnetism, or most of it, and stop producing a magnetic field