Which component stores electrical energy and can retain a charge after power is removed?

Which component stores electrical energy and can retain a charge after power is removed?

• A. Relays store charge
• B. Capacitors store charge
• C. Transformers store charge
• D. Resistors store charge

Answer: (B)

A capacitor stores energy in the electric field between its plates. When connected to a power source, charges accumulate on the plates, creating a voltage across it. After the power is removed, the capacitor can hold that charge for a time, slowly discharging through leakage or a connected circuit. This ability to retain charge is what makes capacitors useful for smoothing voltages and providing brief energy bursts. The stored energy is given by (1/2) C V^2, and how long it lasts depends on how well the capacitor is insulated and its leakage. Other components don’t store a charge: a relay coil or transformer stores magnetic energy briefly while energized, and a resistor dissipates energy as heat instead of storing it.

A capacitor stores energy in the electric field between its plates. When connected to a power source, charges accumulate on the plates, creating a voltage across it. After the power is removed, the capacitor can hold that charge for a time, slowly discharging through leakage or a connected circuit. This ability to retain charge is what makes capacitors useful for smoothing voltages and providing brief energy bursts. The stored energy is given by (1/2) C V^2, and how long it lasts depends on how well the capacitor is insulated and its leakage. Other components don’t store a charge: a relay coil or transformer stores magnetic energy briefly while energized, and a resistor dissipates energy as heat instead of storing it.