Definition
The production of a voltage in one electrical coil caused by a changing magnetic field from a nearby second coil. When current flows through the first coil and changes in strength, its magnetic field expands or collapses across the second coil, inducing a voltage in that second coil without any direct electrical connection between them.
Plain English
Two coils are placed close together. When the electricity in one coil changes, it creates a changing magnetic field that reaches into the other coil and produces a voltage in it -- even though the two coils never touch.
Context Anchor
Seen in aircraft electrical and ignition system discussions, especially with transformers, ignition coils, and magnetos.
Derivation
From Latin mutuus, meaning shared or reciprocal, and inducere, meaning to lead in. The two coils share the effect: one leads a magnetic field into the other.
Why Pilots Care
Mutual induction is the core principle that allows a magneto to generate the high voltage needed to fire spark plugs without relying on battery power.
Grounding Statement
Picture two wire coils sitting close together: if the current in one coil changes, the changing magnetic field around it can create voltage in the other coil.
Intuition Check
Mutual induction does not mean the two circuits are physically connected. The connection is through a changing magnetic field between them.
Example Sentence 1
Mutual induction between the primary and secondary windings of the ignition coil produces the high voltage that fires the spark plugs.
Example Sentence 2
During an ignition system check the mechanic verified that mutual induction was occurring properly by observing consistent spark output.