magnetism and fields

• • the ends of a magnet are called poles - north and south
• law of magnetism

  • when 2 magnets are held tgt, there will be an attractive / repulsive force between them
  • law of magnetism states that 2 like poles repel each other and 2 unlike / opposite poles attract each other
  • the attraction / repulsion is an example of non-contact force
• magnetic materials

  • soft or hard
  • magnetically soft (eg iron) are easy to magnetise and easily lose their magnetism (temporarily magnetised)
  • magnetically hard (eg steel) are difficult to magnetise and don't easily lose their magnetism (permanently magnetised)
  • Electromagnets are made out of magnetically soft materials. This means that electromagnets can be made magnetic or non-magnetic when required
• label

  A) iron

  B) current

  C) steel

  D) attracted

  E) electromagnet

  F) always

  G) permanenet

  H) on

  
• Steel is an alloy which contains iron, so it is also magnetic
• • Magnetic materials (which are not magnets) will always be attracted to the magnet, regardless of which pole is held close to it
  • To test whether a material is a magnet it should be brought close to a known magnet:
  • If it can be repelled by the known magnet then the material itself is a magnet
  • If it can only be attracted and not repelled then it is a magnetic material
• PERMANENT MAGNETS (eg steel)

  • A permanent magnet will produce its own magnetic field and will not lose its magnetism

  INDUCED MAGNETS

  • When a magnetic material is placed in a magnetic field, the material can temporarily be turned into a magnet. This is called induced magnetism
  • When magnetism is induced on a material: One end of the material will temporarily become a north pole and the other a south
  • Magnetic materials will always be attracted to a permanent magnet. This means that the end of the material closest to the magnet will have the opposite pole to magnets pole closest to the material
• When the magnetic material is removed from the magnetic field it will lose most/all ofits magnetism quickly
• • Make sure the pencil you use is sharp to provide a clear and accurate drawing of the field lines
  • Read the marker on the compass from above and not at an angle
  • Allow the compasses to settle for a couple of seconds before taking the reading

  A) compass