The Electric Motor

• What happens to a conductor carrying a current in a magnetic field?

  It experiences a force
• What is the name of the effect when a conductor experiences a force in a magnetic field?

  Motor effect
• How can we determine the direction of the force on a conductor in a magnetic field?

  Using Fleming's left hand rule
• What is the application of the motor effect in electric motors?

  • A loop of wire carrying current
  • Experiences forces in a magnetic field
  • Causes rotation of the loop
• What happens to the current on either side of the loop in an electric motor?

  The current runs in opposite directions
• What forces act on the left and right sides of the loop in a magnetic field?

  Left side acts upwards, right side downwards
• What is the result of the forces acting on the loop?

  The loop rotates in a clockwise direction
• What happens when the loop reaches 90 degrees?

  It stops rotating
• What occurs if the loop rotates beyond 90 degrees?

  The forces push the loop back to 90 degrees
• How can the problem of the loop stopping at 90 degrees be solved?

  By switching the direction of the current
• What device is used to switch the direction of the current in an electric motor?

  Split ring commutator
• What is the function of the split ring commutator?

  It switches the direction of the current
• How does the split ring commutator connect to the electric current?

  Through conducting brushes
• What happens to the current for a tiny fraction of a second during rotation?

  The current switches direction
• What effect does switching the current direction have on the forces acting on the loop?

  Left side force acts upwards, right side downwards
• What does the split ring commutator allow the motor to do?

  Keep rotating in the same direction