NEIEP Mechanics Practice Exam

What three elements are required when operating a motor or generator?

1. Voltage, resistance, torque

2. Magnetic field, current, rotation or movement

3. Power, frequency, capacitance

4. Inductance, capacitance, resistance

The correct answer is: Magnetic field, current, rotation or movement

When operating a motor or generator, the essential elements required are a magnetic field, current, and rotation or movement. The magnetic field is crucial because it provides the necessary environment for electromagnetic induction to occur, which is the principle behind both motors and generators. In a motor, electrical energy is converted into mechanical energy through the interaction of the magnetic field and the current flowing through the windings. Conversely, in a generator, mechanical energy is transformed into electrical energy through this same process of electromagnetic induction. Current is another required element, as it flows through the windings of the motor or generator, interacting with the magnetic field. The presence of current enables the generation of a magnetic force that results in rotation in the case of motors or generates electrical output in generators. Finally, rotation or movement is vital in these devices. For motors, the rotation represents the mechanical output or work done, while for generators, movement refers to the mechanical input necessary to produce electrical energy. Perhaps this movement is derived from a turbine or other mechanical system that drives the generator. Together, these three elements—magnetic field, current, and rotation or movement—define the fundamental operation of both motors and generators in converting energy from one form to another.