Final answer:
Torque is the twisting force that must be developed by a motor to turn its load. It is the rotational equivalent of force and is a measure of the effectiveness of a force in changing or accelerating a rotation.
Step-by-step explanation:
The twisting force that must be developed by a motor to turn its load is called torque. When current is passed through the loops of wire in a motor, the magnetic field exerts torque on the loops, which causes the motor to rotate and perform mechanical work. Torque is the rotational equivalent of force and is a measure of the effectiveness of a force in changing or accelerating a rotation. It is determined by the magnitude, direction, and point of application of the force.