Ham Radio General Class Practice Test

What is the unit used for measuring reactance?

1. Farad

2. Ohm

3. Ampere

4. Siemens

The correct answer is: Ohm

Reactance is a component of impedance that specifically pertains to the opposition that capacitors and inductors provide to alternating current (AC) due to their energy storage properties. The unit of measurement for reactance is the ohm, which is also the unit used for measuring resistance. This means that both resistance and reactance can be expressed in ohms, but they refer to different phenomena in electrical circuits. In the context of reactance, which can be positive (capacitive reactance) or negative (inductive reactance), the ohm signifies how much a component opposes the flow of current in an AC circuit. By understanding that reactance affects the phase relationship between voltage and current, one can appreciate how it impacts circuit behavior. This concept is fundamental in AC circuit analysis and radio communications, where reactance plays a crucial role in tuning and impedance matching. Understanding the implications of reactance is key for ham radio operators, as it helps in optimizing antenna design and performance in various operating conditions.