Universal motor

If you look into a typical DC motor you will see many coils in the armature and many sections to the commutator. One very common motor is called a universal motor. It is actually a series wound electromagnet DC motor as described above.

A universal motor

Such a motor will run on DC or AC. How can this be? When the current reverses direction, as it does many times a second with AC, all the magnet poles reverse.

With an electromagnet motor the attractive and repulsive forces are in the same direction regardless of the polarity of the battery. The motor will operate on AC or DC.

All the attractive and repulsive forces continue to work in the same directions regardless of the voltage polarity; the motor continues to turn in the same direction. Universal motors, sometimes called drill motors, are found in handheld electric drills, vacuum cleaners and many other motorized appliances.