Definition
An electrical component made of wire wound into loops, used to create a magnetic field when current flows through it, or to generate voltage when a magnetic field changes around it. In aircraft, coils are used in ignition systems, relays, solenoids, and instruments.
Plain English
A length of wire wrapped around in loops. Passing electricity through it creates a magnetic field, and a changing magnetic field around it creates electricity. This simple property is the basis of many aircraft electrical parts.
Context Anchor
Seen in aircraft electrical systems, ignition systems, magnetos, relays, generators, and other components that use magnetism to move or produce electricity.
Derivation
From the Old French 'coillir' meaning 'to gather' or 'collect together.' The wire is gathered into loops, and those loops gather magnetic energy when current flows. The shape gives the part both its name and its electrical behaviour.
Why Pilots Care
A faulty coil prevents reliable spark production, which can cause engine misfires or failure to start.
Intuition Check
A coil is not just any curled shape here. In aircraft systems, it usually means wound electrical wire that works with magnetism.
Example Sentence 1
When the ignition coil failed, the engine would not produce a spark on that magneto.
Example Sentence 2
A weak coil can cause intermittent power loss at high altitudes where the spark needs to be strong.