Inductor Energy
Calculate magnetic energy stored in an inductor using E = ½LI². Free online physics calculator with charts, formula breakdown, and accurate joule results.
About This Calculator
The Inductor Energy Calculator computes the magnetic energy stored in an inductor coil when an electric current passes through it. This is a fundamental concept in electromagnetism and electrical engineering — inductors are used in everything from power supplies and transformers to radio frequency circuits and wireless charging systems.
The calculator uses the standard formula E = ½ × L × I², where L is the inductance in henries (H) and I is the current in amperes (A). The result is the stored magnetic energy in joules (J). This energy is proportional to the square of the current, which explains why inductors resist sudden current changes — a high rate of change requires significant energy transfer.
For very small inductor values (microhenries) and low currents, the stored energy is typically in the microjoule or nanojoule range. The calculator automatically switches to scientific notation for small values to ensure readability. The chart modes let you visualize the component contributions to the total energy.
About Inductor Energy
The energy stored in an inductor's magnetic field is analogous to the energy stored in a capacitor's electric field. While capacitors store energy in an electric field proportional to voltage squared (E = ½CV²), inductors store energy in a magnetic field proportional to current squared (E = ½LI²). This duality makes LC circuits capable of sustained oscillation as energy is exchanged between the two components.
Understanding inductor energy is crucial for designing efficient power converters, assessing flyback voltage in relay circuits, and analyzing transient behavior in all inductive loads including motors, solenoids, and electromagnets.
Frequently Asked Questions
What is the energy stored in an inductor?
The energy stored in an inductor is magnetic energy that accumulates in the magnetic field created by the current flowing through the coil. This energy can be released when the current changes, which is why inductors oppose sudden changes in current.
How do you calculate energy stored in an inductor?
Use the formula E = ½ × L × I², where L is the inductance in henries (H) and I is the current in amperes (A). For example, an inductor of 20 μH with 300 mA stores E = 0.5 × 0.00002 × 0.3² = 0.9 μJ of energy.
What units does the inductor energy calculator use?
The calculator uses henries (H) for inductance, amperes (A) for current, and joules (J) for the stored energy. You can enter inductance in any decimal form such as 0.00002 H (20 μH) and current in amperes such as 0.3 A (300 mA).
Why do inductors store energy?
Inductors store energy in their magnetic field when current flows through the coil. The magnetic field represents stored potential energy that can do work when the circuit conditions change. This property makes inductors essential in transformers, power supplies, filters, and LC resonant circuits.
What happens to the stored energy when current changes?
When the current through an inductor changes, the magnetic field either builds up (storing energy) or collapses (releasing energy). This release can cause voltage spikes, which is why you may see a spark when unplugging inductive devices. In LC circuits, this energy oscillates between the inductor and capacitor.
Can I share my inductor energy calculation results?
Yes, the calculator saves your input values in the URL, so you can bookmark or share the exact calculation with anyone. Simply copy the URL after calculating to preserve your inductance and current values.
What are practical applications of inductor energy?
Inductor energy storage is used in switch-mode power supplies for voltage regulation, in LC tank circuits for radio frequency oscillation, in transformers for energy transfer between coils, and in inductive charging systems for wireless power transmission.
How accurate is this inductor energy calculator?
The calculator uses the exact formula E = ½LI² with no approximations. Results are displayed with up to 12 decimal places for precision, and scientific notation is used for very small energy values in the microjoule or nanojoule range.