Inductor Energy Calculator

An inductor stores energy in its magnetic field. When current I flows through inductance L, stored energy is U = ½LI² — directly analogous to capacitor energy U = ½CV². Building current from zero requires doing work against the back EMF ε = −L dI/dt that opposes changes in current (Lenz's law for inductors).

Power delivered to inductor: P = Iε = LI dI/dt. Integrating from I = 0 to I gives U = ∫P dt = ½LI². Energy density in vacuum field is u = B²/(2μ₀); integrating over volume recovers ½LI² for a solenoid.

Example: L = 0.05 H, I = 3 A gives U = 0.5×0.05×9 = 0.225 J — enough to produce a visible spark if current is interrupted suddenly (large dI/dt → large voltage spike V = L dI/dt).

In RL circuits, energy flows from battery into magnetic storage and dissipates in resistor. In ideal LC circuits, energy oscillates between magnetic (L) and electric (C) forms at frequency ω = 1/√(LC).

Practical uses: ignition coils multiply voltage by interrupting primary current; switch-mode power supplies store energy in inductors each cycle; MRI gradient coils are large inductors with significant stored energy (safety concern when quenching).

Real inductors have resistance and core losses; not all input energy remains stored — some heats the winding. At high frequency, skin effect and core hysteresis matter.