Updated: Dec 9, 2025 | Source: 2022-2026 Question Pool | Topic: T5C
T5C03T5C

What describes the ability to store energy in a magnetic field?

Deep Dive: T5C03

The correct answer is D: Inductance. Inductance describes the ability to store energy in a magnetic field. An inductor (coil) stores electrical energy by creating a magnetic field when current flows through it. When current flows through an inductor (a coil of wire), it creates a magnetic field around the coil. Energy is stored in this magnetic field. The amount of energy stored depends on the inductance value (measured in henries) and the current flowing. When the current changes, the magnetic field changes, and the stored energy can be released back into the circuit. Inductors are essential components in radio circuits for filtering, tuning, and impedance matching.

Why Other Answers Are Wrong

Option A: Incorrect. Admittance is the inverse of impedance (how easily current flows), not the ability to store energy in a magnetic field. Option B: Incorrect. Capacitance is the ability to store energy in an electric field, not a magnetic field. Capacitors store energy in electric fields. Option C: Incorrect. Resistance opposes current flow and dissipates energy as heat. It doesn't store energy in a magnetic field.

Exam Tip

Store energy in magnetic field = Inductance. Remember: Inductance is the ability to store energy in a magnetic field. Inductors (coils) do this.

Memory Aid

**I**nductance = **I**nductor **M**agnetic **F**ield (think 'I = IMF' = Inductor Magnetic Field)

Real-World Example

An inductor (coil) in your RF circuit stores energy in its magnetic field. When current flows through the coil, it creates a magnetic field that stores energy. This stored energy can help filter signals or tune circuits. The inductor's inductance value (in henries) determines how much energy it can store.

Source & Coverage

Question Pool: 2022-2026 Question Pool

Subelement: T5C

Reference: FCC Part 97.3

Key Concepts

Inductance Energy storage Magnetic field Inductors

Verified Content

Question from the official FCC Technician Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the T5C topic.