Magnetism Basics

  • All magnetism is caused by moving charges
  • In permanent magnets, the spinning of electrons create magnetism
  • In electromagnets, magnetic fields result from electron flow through a conductor
  • A magnet is any object that produces a magnetic field
  • Magnets have a north pole and a south pole

Magnetic fields

  • Field lines are used to indicate strength and direction of a magnetic field
  • Arrows indicate direction that a force would be applied to the north pole of a magnet if it were put into the field
  • The density indicates the strength of the force (called magnetic flux (B) and measured in Tesla (T))
  • By convention, field lines exit the north pole and re-enter the south pole
  • Field lines coming out of a page are shown by dots
  • Field lines going into a page are shown by crosses

Atoms as magnets

  • Atoms can act as magnets
  • Both electrons and the nucleus have their own magnetic field
  • Spin and orbiting of electrons creates the field

Permanent magnets

  • In most materials, atoms are arranged so that the magnetic fields cancel out
  • In iron and other ferromagnetic materials, groups of atoms, called domains, have electrons with the same orientation
  • The material is not magnetic because the domains cancel out each other’s magnetic fields
  • However, if you put this into an existing magnetic field, all the domains will begin to point in the same direction
  • This results in a permanent magnet, if the field is strong enough to align all of them


  • At room temp, only 4 – iron, nickel, cobalt and gadolinium


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