Energy stored in a linear inductor
Inductive storage and resistive loss are separate.
Key knowledge
A fixed linear inductor with inductance L>0 stores magnetic energy U=LI²/2 relative to zero current. Under passive sign convention v=L dI/dt, so absorbed power vi=dU/dt. Current change can return this energy to the circuit; a real coil’s winding resistance and hysteresis introduce additional losses.
Values and equations
U=½LI²; v=L dI/dt; vi=dU/dt
- U
- Stored magnetic energy J
- L
- Fixed inductance H
- I
- Current entering the passive positive-voltage terminal A
- v
- Passive terminal voltage drop V
- t
- Time s
Conditions and scope
- Constant geometry and linear reversible magnetic response, with a valid lumped inductor model.
- Saturation, hysteresis, changing geometry, significant radiation or mutual coupling require their own energy/flux model. The passive terminal drop has the opposite sign from the self-induced source emf used in a loop orientation.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Read §14.3 linear energy relation14.9 and charging-work integral. Passive drop versus induced emf sign is a disclosed orientation clarification; no universal energy formula for nonlinear/hysteretic cores.
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Entry details
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- foundations-refresh.1
- Structured reference record
- Foundational reference additions