Red Seal Industrial Mechanic (Millwright) Practice Exam

What is the difference between AC and DC motors?

1. AC motors run on alternating current while DC motors run on necessary current

2. AC motors are larger than DC motors

3. AC motors run on alternating current while DC motors run on direct current

4. AC motors are slower than DC motors

The correct answer is: AC motors run on alternating current while DC motors run on direct current

The distinction between AC and DC motors primarily lies in the type of electrical current each type utilizes for operation. AC motors operate using alternating current, which periodically reverses direction, allowing them to efficiently handle power delivery in many industrial and commercial applications. This alternating nature is beneficial for applications where consistent speed and torque are required with lower energy losses. In contrast, DC motors are designed to operate on direct current, which flows in a single direction. This characteristic of DC motors allows for precise speed control and high starting torque, making them suitable for applications that require rapid speed adjustments. Understanding this key difference is vital, as it influences the appropriate choice of motor depending on the specific requirements of an application. The other options presented do not accurately capture the fundamental operational principle distinguishing AC and DC motors. The size comparison and speed considerations mentioned could vary based on specific models and designs rather than the inherent nature of AC and DC motors.