Chapter 5 First- order(一阶) circuits In the chapter we shall introduce the study of circuits characterized by a single energy-storage element-a capacitor or a inductor. It will be shown that the equations describing such a circuit may be put in a form involving an unknown variable and its first derivative. Such an equation is referred to as a first-order differential equation, thus we shall refer to circuits which contain only a single energy-storage element as first-order circuitsChapter 5 First-order（一阶）circuits In the chapter we shall introduce the study of circuits characterized by a single energy-storage element—a capacitor or a inductor. It will be shown that the equations describing such a circuit may be put in a form involving an unknown variable and its first derivative. Such an equation is referred to as a first-order differential equation, thus we shall refer to circuits which contain only a single energy-storage element as first-order circuits