Electrical Engineering: Know It All

Chapter 5

DC Circuit Theory

John Bird

5.1 Introduction

The laws that determine the currents and voltage drops in DC networks are: (a) Ohm’s law, (b) the laws for resistors in series and in parallel, and (c) Kirchhoff’s laws (see Section 5.2). In addition, there are a number of circuit theorems that have been developed for solving problems in electrical networks. These include:

(i) the superposition theorem (see Section 5.3),

(ii) Thévenin’s theorem (see Section 5.5),

(iii) Norton’s theorem (see Section 5.7), and

(iv) the maximum power transfer theorem (see Section 5.9).

5.2 Kirchhoff’s Laws

Kirchhoff’s laws state:

(a) Current Law. At any junction in an electric circuit the total current flowing towards that junction is equal to the total current ...