Electrical Basics – DC Motors

In this video, we eliminate the switch and hook the DC motor right up to the power supply. When we change the polarity, the motor spins in the opposite direction.

The motor has two permanent magnets, usually called the rotor and stator on AC motors; however, because we are dealing with a DC motor, the magnets are NOT rotors or stators. We can tell that the magnets have opposite polarity because they stick together, not repel each other.

The connection points are on the underside of the motor and connect to two metal rods on the motor, which function as brushes. Those rub on the shaft, which has three splits in it and allows for potential difference between any two splits at a time. So, there’s a constant attraction between the motor windings and the permanent magnets as the motor spins; the push-pull action on both sides causes the motor to spin. AC motors have a similar (but not exact) relationship with the magnets.

The DC motor’s speed depends on the voltage at the power supply. This DC motor has stator magnets or field magnets on the outside, the armature that turns, the windings that wrap around the armature, and the commutator (by the brush).