magnetic fields

• the magnetic field is the region around a magnet where a force is exerted on another magnet or magnetic material
• the strength of the magnetic field depends on the distance from the poles of the magnet
• the magnetic field is strongest at the poles of a magnet
• the magnetic field lines are used to represent the strength and direction of a magnetic field:

  • direction is shown through an arrow
  • the strength is shown through the spacing of the magnetic field lines. If the magnetic field lines are lose together, the magnetic field will be strong. If the magnetic field lines are far apart, the magnetic field will be weak
• the direction of a magnetic field line goes into the south pole and out of the north pole, or the direction a north pole would move if placed into the field
• field lines must never touch or cross other field lines
• magnetic compass to draw field lines:

  1. place your bar magnet on a piece of paper and trace around the magnet
  2. draw a dot at one end of the magnet, near its corner
  3. place your plotting compass next to the dot, and draw a new dot where the compass' north pole is
  4. move the compass' south pole to the dot, and repeat the process of plotting the north pole and moving the south pole to that dot until you get a full magnetic field line
  5. repeat from various points around the magnet at both poles to create any field lines
  6. once complete, the points should be joined with a line and an arrow drawn
• on earth, in the absence of any magnet or magnetic material, a magnetic compass will always point north, and this is evidence that the core of the earth is magnetic and creates its own magnetic field
• a magnetic compass contains a small bar magnet and the compass needle points in the direction of the Earth's magnetic field
• the geographical south pole on earth is the magnetic north pole