# Series Circuit Elements:

## Introduction

Circuit elements are said to be connected in series if all of the elements carry the same current. An example of two circuit elements connected in series is shown in Fig. 1. Applying KCL at node a and taking currents out of the node as positive, we see that:

 $- {i_1} + {\rm{ }}{i_2} = {\rm{ }}0$ Or ${i_1} = {\rm{ }}{i_2}$ (1)

Equation (1) is a direct outcome of the fact that the (single) node a in Fig. 1 interconnects only two elements—there are no other elements connected to this node though which current can be diverted. This observation is so apparent (in many cases1) that the equation on the right is generally written by inspection for series elements such as those shown in Fig. 1 without explicitly writing KCL.

#### Note:

Series circuit elements share the same current. Elements in series can be recognized in two ways:

• If two and only two elements are connected to a single node, the elements are in series.
• If applying KCL at a node results in the conclusion that the currents in two elements are identical, the elements are in series.

1. List which of the elements in the circuit below are in series.
2. List which of the elements in the circuit below are in series.
3. List which of the elements in the circuit below are in series.
4. List which of the elements in the circuit below are in series.