electric motors

• when a current carrying conductor is placed in a magnetic field it experiences a force . this is called the motor effect
• the motor effect is caused by the field created by the current interacting with the magnetic field
• the force can be increased by

  • the size of the current
  • the length of the conductor in the magnetic field
  • the flux density
• reversing the direction of either the current or the magnetic field will cause the direction of the force to reverse
• the direction of the force can be found using flemmings left hand rule
• electric motors

  • a current carrying coil in a magnetic field will rotate
  • this is because the current going up one side of the coil is in the opposite direction to the current coming back down
  • the coil rotates continuously
• the brush contacts at the commutator ensure that the current direction in the coil is always the same
• increasing the current or magnetic field will make the motor rotate faster
• reversing the current or the magnetic field will make the motor rotate in the opposite direction