Inductor Energy
Energy stored in a magnetic field.
Formula
Variables
How it works
When current flows through an inductor, it creates a magnetic field around the coil, and building that field takes energy. The amount stored depends on both the inductance, which measures how strongly the coil resists changes in current, and on the square of the current, so doubling the current makes the stored energy four times larger. This relation comes from integrating the voltage needed to increase the current in an inductor over time.
When to use it
Use this formula when you need the energy stored in a coil, solenoid, or other inductor at a given current. It is common in power electronics, inductive kickback analysis, and when estimating how much energy can be released by a magnetic component.
Worked example, step by step
An inductor has an inductance of 0.75 H and carries a current of 4.0 A. E = 1/2 × L × I^2 E = 1/2 × 0.75 × (4.0)^2 E = 0.375 × 16 E = 6.0 J Final answer: the energy stored in the inductor is 6.0 joules.
Common mistakes to avoid
- Using the current instead of current squared
- Forgetting to convert inductance to henries before calculating
- Confusing stored magnetic energy with electrical power, which is measured in watts rather than joules
Did You Know?
An inductor stores energy in its magnetic field and resists sudden current changes, smoothing power supplies.
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