In a mechanical transmission system an electric motor is also called a __________.

• A. prime mover
• B. actuator
• C. engine
• D. driver

Answer: (A)

The main idea here is the role of a prime mover: it’s the primary source of power that drives a mechanical system by converting energy into motion that feeds the transmission. An electric motor does this by taking electrical energy and turning it into rotational mechanical energy (torque) that drives the gears, belts, and shafts of the transmission. That makes it the essential energy source for the system’s motion.

An actuator, while it can create motion, is usually a component within a control system rather than the overall power source. An engine typically refers to combustion-based power, not electric, so it’s not the correct general term for an electric motor. A driver isn’t used to name the power source in this context.