Ham Radio General Class Practice Test

Which of the following is responsible for opposing alternating current in an inductor?

1. Conductance

2. Reluctance

3. Admittance

4. Reactance

The correct answer is: Reactance

In an inductor, the phenomenon that opposes alternating current is known as reactance. Reactance is the resistance encountered by the alternating current due to the inductance, which causes a delay in the current flow through the inductor. When an AC voltage is applied to an inductor, it generates a magnetic field that stores energy. The effect of this changing magnetic field is what causes the current to lag behind the voltage, leading to the opposition to current flow. Reactance can be thought of as a dynamic resistance to AC signals, and it is frequency-dependent. The higher the frequency of the alternating current, the greater the reactance, which ultimately impedes the flow of current. This characteristic distinguishes reactance from other types of opposition in electrical components, such as resistance, which applies to direct current, and helps in designing circuits that deal with AC signal processing. Understanding reactance is crucial for those involved in radio communications and electronics since it affects how components like inductors behave in AC circuits.