In a magnetic energy storage element used in circuits, which component is typically used?

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

Answer: (C)

Magnetic energy in circuits is stored by an inductor. When current flows through a coil, a magnetic field builds around the winding and that field contains energy, with the amount proportional to the inductance and the square of the current (E = 1/2 L I^2). This makes inductors ideal for storing energy magnetically and for applications like smoothing current, energy transfer in switching power supplies, and filtering. Capacitors store energy in an electric field between plates, not a magnetic one, so they’re the electrical-energy storage element. Resistors simply dissipate energy as heat, and diodes are nonlinear components that don’t store energy. So the correct choice is the inductor.