Magnets & Electromagnetism

• permanent magnet

  a material that is always magnetic
• poles

  where magnetic forces are the strongest
• induced magnet

  a material that becomes a magnet when placed into a magnetic field
• magnetic flux density

  strength of magnetic lines per m^2
• tesla

  unit where magnetic flux is measured
• the direction of field lines are north to south
• like poles repel
• opposite poles attract
• plotting a magnetic field

  • plot compass
  • line up compass with field lines
  • plot lines by joining points up with compass
• solenoid

  a coil of wire that can become a magnet when current flows in
• ways to strengthen solenoid fields

  • increase coils
  • increase current
• ways to make an electromagnet stronger

  • iron core
  • increase coils
  • increase current
• force = magnetic flux density x current x length