Inductor Energy Calculator NZ
This calculator finds the energy stored in an inductor's magnetic field from its inductance and the current flowing through it. An inductor, typically a coil of wire, stores energy not in an electric field like a capacitor, but in the magnetic field created by the current passing through it. The energy is half the inductance times the current squared, a form that mirrors the kinetic energy of a moving mass, with inductance playing the role of mass and current the role of velocity. This stored energy is central to how inductors behave: it is why the current through an inductor cannot change instantly, why switching an inductive circuit can produce voltage spikes, and how energy is shuttled in switching power supplies, motors and transformers. This tool computes it. You enter the inductance in henries and the current in amperes, and the calculator returns the energy stored in joules, along with the inductance and current for reference and the magnetic flux linkage, the inductance times the current. The results update as you type. Use it for electronics and physics study, for designing inductive circuits, or to understand energy storage in coils. Because the energy depends on the square of the current, doubling the current quadruples the stored energy, which is why high-current inductors store and release substantial energy and why suddenly interrupting that current is what causes the large voltage spikes seen across switches and relays. The flux linkage, the product of inductance and current, is the magnetic equivalent of momentum and relates to the voltage induced when the current changes. Inductance is often small, measured in millihenries or microhenries, so you may enter fractional or scientific-notation values for typical components.
Energy = half x inductance x current squared. Energy grows with the square of current. Flux linkage = inductance x current. Inductors store energy in their magnetic field.
How it works
The energy stored in an inductor is one half of its inductance multiplied by the square of the current through it. This mirrors the kinetic energy of a moving mass. The flux linkage, the inductance times the current, is shown alongside; it is the magnetic quantity whose rate of change gives the induced voltage.
Worked example
For an inductor of 0.5 henries carrying a current of 2 amperes, the energy stored is one half of 0.5 times 2 squared, which is 0.5 times 0.5 times 4, equals 1 joule. The flux linkage is 0.5 times 2, which is 1 weber. Doubling the current to 4 amperes would raise the stored energy to 4 joules.
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