How Does a Capacitor Store Energy?

A capacitor consists of two conductive plates (usually metal foil) separated by a dielectric (insulating material such as ceramic, plastic film, or electrolyte). When voltage is applied, electrons accumulate on one plate and are depleted from the other, creating an electric field across the dielectric that stores energy. The capacitance (measured in farads) depends on plate area, dielectric thickness, and dielectric constant. Unlike batteries, capacitors charge and discharge almost instantly, making them ideal for filtering, smoothing power supplies, and delivering quick energy bursts. Supercapacitors (ultracapacitors) use high-surface-area materials like activated carbon and can store hundreds of times more energy than conventional capacitors.