Construction: A motor require essentially a rectangular coil called armature a permanent magnet, a device called commutator to reverse the direction of current and a source of electrical energy like a battery. A shaft is connected to the armature to utilize the mechanical energy so produced.

The rectangular coil ABCD and iron core together constitute the armature. The armature is mounted on the shaft. Two metallic rings C₁ and C₂ insulated from each other are mounted on the shaft act as commutator.

The ends of ABCD coil are soldered to C₁ and C₂. The wires from battery B are connected to carbon brushes B₁ and B₂ which are always in contact with half rings C₁ and C₂.

The battery B, the key K, the brushes, the commutator and coil form an electric motor.