Introductory Electrical Engineering With Math Explained in Accessible Language

5Resistors: The Most Fundamental Component

5.1 Introduction

This chapter is about resistors, the most basic electric component.

5.2 Resistor

Resistors are the most fundamental and commonly used of all the electronic components.

Having two terminals, this component opposes current flow. This opposition is called electric resistance, measured in Ohms, and is represented by the Greek letter omega (Ω) in the SI.

5.3 Electric Resistance

All materials offer, to a certain degree, resistance to the flow of electrons. Metals, for example, offer very little electric resistance, but the resistance is there and it is not 0.

Factors like surface area, thickness, and chemical properties can alter electric resistance, and by manipulating these characteristics correctly, several types of resistors can be created.

5.4 Symbols

There are two different symbols to represent a resistor in schematics, one in the American standard and the other in the international standard. Figure 5.1 shows both symbols.

Figure 5.1 Resistor symbol (US and international standard).

Figure 5.2 Real standard resistors.

Figure 5.2 shows a picture of real resistors where color stripes describing their resistance values and other characteristics can be seen around their bodies.

5.5 Types of Resistor

There are ...