What does the term "torque" refer to in motor control?

The term "torque" refers specifically to the rotational force produced by the motor, which is a key parameter in motor control. Torque is what allows the motor to perform work, such as turning the shaft against a load. It is measured in units of force multiplied by distance (e.g., Newton-meters or pound-feet) and is crucial in determining how effectively a motor can accomplish tasks like driving machinery or other mechanical systems.

Understanding torque is essential for motor control because different applications may require varying levels of torque at different speeds. For instance, starting a heavy load typically demands high torque, whereas maintaining a load often requires lower torque but at higher speeds. Torque is directly related to the motor's efficiency and performance, influencing how well it meets the specific demands of the application it serves.

The other terms mentioned in the options refer to different aspects of motor operation that do not define torque. The speed of rotation is a measure of how fast the motor's rotor turns, while the electrical input required to start the motor relates to the initial power demands at startup. The efficiency ratio involves how effectively the motor converts input energy into useful output, which is a separate consideration from torque itself.