DC electric motor

There are 4 main features of a DC motor


  • This is a frame in which the coil of wire is wound.
  • It rotates when a current flows through the coil of wire due to the motor effect.
  • This is the moving part of the motor, it converts Electrical energy into Kinetic Energy.


  • This is the two stationary magnets on the sides of the motor.
  • It can be made from permanent magnets or electromagnets.
    • Permanent magnets are simply stuck onto the side of the motor.
    • Electromagnets can be made by using a soft iron core shaped like a C with coils of wire wrapped around it.
  • The magnets do not have to be bar magnets, it can be radial to ensure a constant magnetic torque in the armature.
  • This is what provides the magnetic field for the motor effect to happen in the armatures.

Split Ring Commutator

  • This is a device that reverses the direction of a current flowing through an electric motor.
  • Really, it is conducting ring with a split in the middle which has one side of the split connected to one armature and the second armature to the other side.
  • It is able to do this as the contacts with the power supply are not moving, simply the armatures.
  • [diagram missing]
  • See it in action on eye-burningly terrible colour schemes. http://www.walter-fendt.de/ph14e/electricmotor.htm
  • The role of this commutator is to keep the current in the armatures relatively constant to the magnetic field, ensuring that it will spin in the same direction as long as the motor is functioning.
  • Without the Split Ring Commutator, the current would cause the rotors to spin in the opposite direction after reaching the zero torque point (RH Rule) and it will oscillate until it stops perpendicular to the field.

Conducting Brushes

  • These are conductors that make electrical contact with the moving split ring of the commutator.
  • It is there to close and complete the circuit.