ARRL Technician Practice Exam

What is the ability to store energy in a magnetic field called?

1. Inductance

2. Capacitance

3. Resistance

4. Reactance

The correct answer is: Inductance

The ability to store energy in a magnetic field is known as inductance. This phenomenon occurs in electrical circuits where the current flowing through a conductor produces a magnetic field around it. When the current changes, the magnetic field also changes, and this changing magnetic field induces an electromotive force (EMF) that opposes the change in current. Inductors, which are components designed to take advantage of this effect, store energy in the magnetic field created around them as current passes through. Capacitance, on the other hand, refers to the ability of a component, like a capacitor, to store electrical energy in an electric field, not a magnetic field. Resistance is a measure of how much a component resists the flow of current, and reactance is the opposition to alternating current due to inductance and capacitance, but it does not specifically pertain to the storage of energy in a magnetic field. Thus, inductance is the correct term that specifically identifies the capacity to store energy in a magnetic field.