Capacitors & Capacitance — A/L Physics

Capacitor A device that stores electrical energy in an electric field. A capacitor consists of two conductors (plates) separated by an insulator (dielectric). When connected to a battery, equal and opposite charges accumulate on the plates, creating a potential difference. Example: The flash unit in a camera charges a capacitor rapidly, then discharges it to produce a bright flash.

Capacitance (C) The ability of a capacitor to store charge per unit potential difference. Mathematically, C = (Q)/(V) . A larger capacitance means more charge can be stored at a given voltage. Capacitance depends only on the geometry of the plates and the material between them, not on Q or V . Intuition: A bigger bucket (larger area) holds more water (charge) at the same water pressure (voltage).