What is the turning effort or twist that a shaft sustains when transmitting power called?

• A. Transformer
• B. Servo
• C. Solenoid
• D. Torque

Answer: (D)

Torque is the turning effort a shaft experiences as it transmits power. It represents the rotational force that causes the shaft to twist around its axis. This twisting effect comes from applying a force at some distance from the axis, and it's quantified by the relationship that torque equals force times lever arm. In rotating systems, the power transmitted is tied to both torque and how fast the shaft is turning: P = T × ω, where ω is angular velocity. So the amount of torque directly governs how much rotational work the shaft can do at a given speed. Torque is measured in newton-meters (N·m) or foot-pounds (ft·lbf). The other terms refer to different devices: a transformer changes voltage/current, a servo is a motor with feedback control, and a solenoid is a linear actuator. None describe the twisting force on a shaft the way torque does.