Definition
A numerical value, between 0 and 1, that expresses how much of the magnetic field produced by one coil links with a second coil placed near it. A value of 1 means all of the magnetic flux from the first coil passes through the second coil; a value of 0 means none of it does. The coefficient depends on the spacing, orientation, and core material shared between the two coils.
Plain English
A number that tells you how well two coils are sharing their magnetic field. The closer the number is to 1, the more tightly they are linked. The closer it is to 0, the more independent they are.
Context Anchor
Seen in aircraft electrical and avionics theory, especially when studying transformers, ignition coils, and other circuits that use magnetism to transfer energy.
Derivation
‘Coefficient’ comes from Latin roots meaning ‘working together,’ and is used in science to mean a number that measures a relationship. ‘Coupling’ means joining or linking. Together, the term describes a number that measures how strongly two coils are linked through their shared magnetic field.
Why Pilots Care
Maintenance technicians and pilots studying aircraft systems encounter this when learning how transformers and ignition coils transfer energy. Tighter coupling means more efficient energy transfer; looser coupling means losses, which affects how components like magnetos and avionics transformers are designed and troubleshot.
Grounding Statement
If two coils are close together and lined up well, more of the first coil’s magnetic field reaches the second coil, so the Coefficient Of Coupling is higher.
Intuition Check
Do not think of coupling here as a physical connector or clamp. In this context, it means magnetic linkage between two coils.
Example Sentence 1
The transformer in the avionics power supply uses a shared iron core to give the two windings a high coefficient of coupling.
Example Sentence 2
A high coefficient of coupling in the ignition coil improves spark reliability.