Capacitors and Dielectrics
Capacitance Capacitance is the measure of an object’s ability to store electric charge. Key Points The unit of capacitance is known as the farad (F), which can be equated to many quotients of units, including JV -2 , WsV -2 , CV -1 , and C 2 J -1 . Capacitance (C) can be calculated as a function of charge an object can store (q) and potential difference (V) between the two plates: C = q V C = q V Q depends on the surface area of the conductor plates, while V depends on the distance between the plates and the permittivity of the dielectric between them. In storing charge, capacitors also store potential energy, which is equal to the work (W) required to charge them. For a capacitor with plates holding charges of +q and -q, this can be calculated: W stored = CV 2 2 W stored = CV 2 2 . The above can be equated with the work required to charge the capacitor. Key Terms dielectric : An electrically insulating or nonconducting material considered for its electr...