FCC Question Pool Review

Technician Class (Element 2) • 2022-2026

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Question T5C04

From subelement T5 - T5C

T5C04
Answer: C

What is the unit of inductance?

AThe coulomb
BThe farad
CThe henry
DThe ohm

Why is this correct?

The henry is the unit of inductance, which measures a component's ability to store energy in a magnetic field. Inductors are typically coils of wire that create magnetic fields when current flows through them. The coulomb measures electric charge, the farad measures capacitance (energy storage in electric fields), and the ohm measures resistance or impedance (opposition to current flow).

Memory tip

Remember the pairing: capacitance uses farads for electric field energy storage, while inductance uses henries for magnetic field energy storage. Both are named after scientists (Michael Faraday and Joseph Henry). This parallel structure helps distinguish between the two fundamental energy storage mechanisms in electronics.

Learn more

In practical amateur radio circuits, inductance values are typically measured in microhenries (μH) or millihenries (mH). Antenna tuners use inductors to match impedances, and RF chokes use high inductance to block unwanted RF currents. The henry unit, like the farad for capacitors, represents the fundamental electromagnetic property that makes resonant circuits and filters possible in your station equipment.

Think about it

Why do you think inductors and capacitors are often used together in amateur radio circuits, and what happens when their energy storage effects interact?