Definition
The production of a voltage in a coil caused by a change in the current flowing through that same coil. When current through a coil changes, the magnetic field around the coil expands or collapses, and this changing field induces a voltage back into the coil itself. The induced voltage opposes the change in current that produced it.
Plain English
When the current flowing through a coil changes, the coil generates its own voltage that pushes back against that change. The coil essentially resists having its current changed quickly.
Context Anchor
Seen in aircraft electrical and ignition-system discussions, especially when studying coils, magnetos, and circuits being switched on or off.
Derivation
From Latin 'inducere,' meaning 'to lead in.' 'Self' indicates the coil induces a voltage in itself, rather than in a separate nearby coil (which would be mutual induction). The name describes exactly what happens: the coil leads a voltage into itself through its own changing magnetic field.
Why Pilots Care
Self-induction is what makes ignition systems work. When the primary circuit in a magneto is suddenly broken, self-induction in the coil produces the high voltage needed to fire the spark plugs. It also explains why opening a switch on an inductive circuit can produce a spark or arc at the contacts.
Grounding Statement
Picture current in a coil being switched off: self-induction is the coil’s electrical pushback against that sudden change.
Intuition Check
Self-induction does not mean electricity starts by itself. It means a changing current creates a voltage in the same wire or coil that is carrying that current.
Example Sentence 1
Self-induction in the magneto's primary coil generates the high voltage that fires the spark plugs each time the breaker points open.
Example Sentence 2
Technicians check for weak self-induction when troubleshooting low output from an aircraft alternator.