With the requisite background information of the first two chapters now behind us, in this chapter we shall begin our analysis of electrical circuits. Here we will introduce the most simple configuration, the series loop. It can contain any number of resistors and voltage sources, or in place of the voltage sources, a single current source. We shall examine how to determine the current flow through each component, the voltage across each component and the power either dissipated or generated by each component. Other practical issues will also be examined, such as the effect of component tolerance on the circuit parameters.