Definition
An inductor whose inductance value can be adjusted, typically by moving a ferromagnetic core in and out of the coil or by changing the number of active turns in the winding. Used in tuned circuits where the inductance must be set or adjusted to match a desired frequency or response.
Plain English
A coil that stores energy in a magnetic field, built so its strength can be dialed up or down — usually by sliding a metal core deeper into the coil or pulling it out.
Context Anchor
Seen in avionics, radio, and electrical system maintenance descriptions, especially in circuits that must be tuned or calibrated.
Derivation
From Latin 'inducere' meaning 'to lead in' — referring to how a changing current in the coil 'leads in' or induces a voltage. 'Variable' simply means the value can be changed rather than fixed.
Why Pilots Care
Allows precise tuning of radio receivers and transmitters so the correct frequency is selected and the signal remains clear.
Intuition Check
Variable does not mean random or unreliable here. It means adjustable within a designed range.
Example Sentence 1
The technician adjusted the variable inductor to bring the antenna into resonance with the transmitter's operating frequency.
Example Sentence 2
During preflight checks the mechanic verified that the variable inductor in the ADF tuner still moved smoothly across its range.