Chapter | 4 Capacitors 71 where Q is the charge measured in coulombs, C is the capaci- tance, and V is the voltage. From this we can see that a charge of 1 coulomb is stored by a capacitor of 1 farad, when a voltage of 1 volt is applied. Alternatively, we may define the farad (as we promised we would, earlier in the chapter) as being the capacitance that will store a charge of 1 coulomb when a voltage of 1 volt is applied. We can now understand why it is that changing the capacitor value changes the time constant, and hence changes the associated time delay in the changing voltage across the capacitor. Increasing the capacitance, say, increases the charge stored. As the current flowing is determined by the resistance in the circuit, and is thus fixed at any particular voltage, this increased charge takes longer to build up or longer to decay away. Reducing the capacitance reduces the charge, which is therefore more quickly stored or more quickly discharged. Similarly, as the resistor in the circuit defines the current flow- ing to charge or discharge the capacitor, increasing or decreasing its value must decrease or increase the current, therefore increas-