An inductor stores energy in its magnetic field. The energy is proportional to inductance and the square of current. Doubling current quadruples stored energy. Inductors oppose rapid current changes, making them useful for filtering and energy storage in switching power supplies.
⚠Never open an inductor circuit suddenly! The induced voltage V = L dI/dt can reach thousands of volts. Always use a flyback diode or snubber for protection.
Inductor vs Capacitor Energy Storage
Both inductors and capacitors store energy, but in different forms. Inductors store in magnetic fields (proportional to current squared). Capacitors store in electric fields (proportional to voltage squared). Inductors oppose current changes, capacitors oppose voltage changes. Together they form resonant circuits.
Magnetic Energy
E = ½LI². Energy in magnetic field around coil. Proportional to current squared. Released when current drops.
Inductor Applications
Power supply filters, DC-DC converters (boost/buck), RF circuits, chokes, transformers, and motor windings.
Energy Density
Inductors store less energy than capacitors per volume. Typical: 0.1-10 mJ for small inductors. Large power inductors: up to hundreds of joules.
Comparison
Capacitor: E=½CV² (electric field). Inductor: E=½LI² (magnetic field). Capacitors store more energy typically, but inductors handle high currents better.
Teaching Example: L=10mH (0.01H), I=1A.
E = ½ × 0.01 × 1² = ½ × 0.01 × 1 = 0.005 J = 5 mJ.
Compare: A 1000μF capacitor at 12V stores ½×0.001×144 = 72 mJ (14× more for similar component size).
E = ½×L×I². A 10mH inductor at 1A stores 5mJ. A 1H inductor at 10A stores 50J. Energy increases with current squared.
Inductor vs capacitor energy?▼
Capacitors store in electric field (E=½CV²). Inductors store in magnetic field (E=½LI²). Capacitors have higher energy density typically.
What is the inductor voltage equation?▼
V = L × dI/dt. Voltage is proportional to the rate of current change. Rapid current change = high voltage. Used in boost converters and spark ignition.
Why use a flyback diode?▼
When current is interrupted, the inductor generates a high-voltage spike (V = L dI/dt). A flyback diode provides a safe path for the current to decay, protecting transistors and switches.
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