magnetism and the motor effect

• poles of a magnet

  • north
  • south
• magnetic forces - non contact
• opposite poles - attract
• like poles - repel
• magnet - an object capable of exerting a magnetic force
• permanent magnet - always magnetic
• induced magnet - becomes a magnet when it is in a magnetic field
• right hand rule

  • fingers - direction of magnetic field
  • thumb - direction of current
• motor effect

  • when 2 magnetic fields interact
• magnetic flux density - strength of magnetic field
• force = magnetic flux density x current x length
• magnetic flux density is measured in Tesla
• Fleming's left hand rule

  • index finger - magnetic field ( north to south )
  • middle finger - direction of current ( positive to negative )
  • thumb - direction of force
• split ring commutator - part of a dc electric motor that reverses the direction of the current every half turn of the coil