Ham Amateur Radio Technician Practice Exam

What is reactance?

1. Resistance to direct current

2. Opposition to the flow of alternating current

3. Voltage drop in a circuit

4. Current increase in a circuit

The correct answer is: Opposition to the flow of alternating current

Reactance refers to the opposition that a circuit element presents to the flow of alternating current (AC) due to its inductance or capacitance. Unlike resistance, which dissipates energy as heat in a circuit, reactance stores energy temporarily. In AC circuits, reactance can significantly affect how energy is transferred through the circuit. It can be broken down into two types: inductive reactance, which is associated with inductors, and capacitive reactance, related to capacitors. Both types of reactance vary with frequency, meaning the opposition they provide changes depending on the frequency of the AC signal. Understanding reactance is crucial for analyzing and designing circuits that operate with alternating current, as it directly impacts the overall impedance of the circuit and affects the phase relationship between voltage and current.