Inductor Energy
Stored energy in a current-carrying inductance.
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The engineering
The magnetic twin of ½CV², with a temper: capacitors tolerate open circuits, inductors do not tolerate them. Interrupt the current and the energy exits through whatever voltage it takes — that's your relay-coil arc and your flyback converter, same physics, different paperwork.
Freewheel diodes exist because this card's number has to go somewhere.
Where this math comes from
Joseph Henry watched sparks jump when he broke inductive circuits in 1832 — self-induction announcing itself as stored energy with an attitude. The ½LI² bookkeeping followed with Maxwell's field-energy formulation.
The induction coil (Ruhmkorff's, famously) weaponized the effect for early high-voltage physics, and every ignition system since is Henry's spark, scheduled.
- 1832Joseph HenrySelf-induction discovered (the henry remembers him).
- 1851Heinrich RuhmkorffInduction coil — stored magnetic energy as a product.
- 1873James Clerk MaxwellField-energy formulation — ½LI² formalized.
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