Capacitance and Uses of Capacitors
unpolarised capacitor symbol polarised capacitor symbol Capacitance Capacitance (symbol C) is a measure of a capacitor's ability to store charge . A large capacitance means that more charge can be stored. Capacitance is measured in farads, symbol F. However 1F is very large, so prefixes (multipliers) are used to show the smaller values: µ (micro) means 10 -6 (millionth), so 1000000µF = 1F n (nano) means 10 -9 (thousand-millionth), so 1000nF = 1µF p (pico) means 10 -12 (million-millionth), so 1000pF = 1nF Charge and Energy Stored The amount of charge (symbol Q) stored by a capacitor is given by: Charge, Q = C × V where: Q = charge in coulombs (C) C = capacitance in farads (F) V = voltage in volts (V) When they store charge, capacitors are also storing energy: Energy, E = ½QV = ½CV² where E = energy in joules (J). Note that capacitors return their stored energy to the circuit...