the motor effect

• the motor effect occurs when a current-carrying conductor is placed in a magnetic field and the magnet producing the field and conductor exert a force on each other
• the direction of the force on the wire or conductor depends on the direction of the current and direction of the magnetic field
• Flemming's Left Hand Rule:

  • first finger (index) follows the magnetic field
  • middle finger follows current
  • thumb shows the direction of the force
• factors that affect the size of force on the conductor in the motor effect:

  • increasing the current flowing through the wire increases the strength of the magnetic field so a greater force is exerted
• factors that affect the size of the force on a conductor in the motor effect:

  • using stronger magnets increases the magnetic field between the poles of the magnet, so a greater force is exerted
• factors affecting the size of the force on a conductor in the motor effect:

  • placing the wire at 90 degrees to the direction of the magnetic field lines between the poles of the magnet, as this means more field lines will be cut and maximum interaction between the two magnetic fields and so force exerted
• if the two magnetic fields are parallel, there will be no interaction between the two magnetic fields and therefore no force exerted
• reversing the direction of either the field or the current means the direction of the force is reversed
• by reversing the direction of both the field and the current, the direction of the force will stay the same
• F = B x I x L only works for conductors at right angles to a magnetic field and carrying a current