Which component stores energy in a magnetic field and resists changes in current?

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

Answer: (B)

Inductors store energy in a magnetic field and resist changes in current. When current flows through a coil, a magnetic field builds up and stores energy (proportional to the square of the current). If the current tries to change, the changing magnetic field induces a voltage that opposes that change, known as back emf, making it harder for the current to increase or decrease quickly.

That’s different from a resistor, which simply dissipates energy as heat with no energy storage; a capacitor, which stores energy in an electric field and tends to oppose changes in voltage rather than current; and a diode, which mainly controls the direction of current flow and does not store magnetic energy.