Which component stores energy in a magnetic field?

• A. Capacitor
• B. Resistor
• C. Inductor
• D. Diode

Answer: (C)

An inductor stores energy in a magnetic field. When current flows through a coil, it creates a magnetic field around the winding, and the energy tied up in that field is E = 1/2 L I^2, where L is the inductance set by the number of turns, core material, and geometry, and I is the current. This stored energy is what gives inductors their characteristic behavior: they resist changes in current because altering the current changes the magnetic energy.

For context, a capacitor stores energy in an electric field between its plates (E = 1/2 C V^2), while a resistor dissipates energy as heat and a diode mainly governs current flow without storing energy. The magnetic-field energy focus marks inductors as the components responsible for magnetic energy storage.