Toys and other inexpensive items often contain permanent-magnet DC motors. Therefore, this type of motor is one of the easiest for experimenters to obtain. The stator consists of permanent magnets that provide a constant magnetic field. Current is passed to the armature windings via brushes and commutator segments. M agnets inside the motor cause it to spin one direction or another depending upon polarity.
Some motors contain no gears and spin very fast, and have little if any torque.
Torque is the measure of how hard the motor can push. To produce more torque, these motors must be geared down. Highly geared motors have a significant amount of torque, but are slow. The ideal motor maintains a good balance of torque and speed. Making a motor run forward, backwards, and turning it off are easy using Interactive C. Figure 1.