Which term is defined as the measurement of opposition to current flow in an electrical circuit?

• A. Nominal Voltage
• B. Hazard Analysis
• C. Impedance
• D. Monitoring

Answer: (C)

Impedance is the measurement of opposition to current flow in an electrical circuit. In an AC system it combines resistance (the steady opposition to current) with reactance (the opposition caused by energy storage in inductors and capacitors). The overall effect is quantified in ohms and determines how much current will flow for a given voltage, described by the relationship I ≈ V / Z. In DC circuits, reactance disappears, so impedance reduces to just resistance. Understanding impedance helps explain how circuits behave, including how devices like motors or controllers respond to different voltages and frequencies.

Nominal voltage is simply the rated voltage of a system, not the opposition to current. Hazard analysis is about evaluating potential risks and hazards, not electrical opposition. Monitoring refers to observing and measuring system conditions, not a property that describes current flow.