A device for changing electrical energy into rotational movement. The turning power or torque of a motor can vary greatly. Generally speaking small motors have low torque whereas large motors usually have a high torque rating. Motors come in ac and dc versions, dc types of between 3 - 12 volts being most suitable for general use. The current direction controls the direction of rotation for dc motors.
It is usually necessary to "gear down" a motor as their speed of rotation - typically 2400rpm is too great This can be achieved either mechanically or electronically. DC motors have the advantage of being relatively inexpensive and can be obtained in high torque versions which are most suitable for driving models.