A DC motor is a simple electric motor, powered by direct current.
Its main components are the rotor (rotary part) and the stator (stationary part). The stator is a permanent magnet, which surrounds the rotor. The rotor consists of at least one coil that is wound around an iron core (that is, an electromagnet).
When electric current is supplied to the metal coil, a magnetic field is generated around it. Therefore the coil will function as a magnet: it will turn in order to align itself with the permanent magnetic field of the stator. However, once it reaches a stable position, the commutatorswitches the direction of the electric current. This causes the rotor to continue to turn in search of the stable position. It will continue to rotate as long as the motor receives a supply of electric current.
The coil receives its power supply via the ring segments of the turning commutator, which, in turn, receives power supply via the brushes. The brushes are usually made of carbon, since as they wear out, the microscopic carbon dust particles are easily expelled from the rotating motor. If the brushes were made of metal, the metal particles would be deposited on the commutator, causing a short-circuit. When we see sparks in an operating electric motor, they are formed at the brushes.
Electric motors that consist of a single coil have a position from which they cannot restart. More complex DC motors, therefore, contain more than one coil, so their operation is continuous and they can always start. In these, the commutator consists of not two, but several ring segments. There are also DC motors in which the stator is an electromagnet too.
coil - When electric current is fed into a metal coil, a magnetic field is generated around the coil, that is, it will function as a magnet: it will turn in order to align itself with the permanent magnetic field of the stator.
commutator - The commutator rotates together with the rotor of the DC motor. It receives electric current from the brushes and transmits it to the coil(s) of the rotor. In the simplest DC motor there are two poles, therefore the commutator consists of two segments. As the commutator rotates, the poles of the electric current are switched every 180°.
brush - Electric current flows through the brush onto the commutator, then to the coil. It is usually made of carbon.
iron core - The function of the iron core is to strengthen the magnetic field that is created by the coil.