EMT 1150 Notes - Summary Introductory Circuit Analysis PDF

Preview

Summary

Summary chapter 2...

Description

EMT 1150 NOTES (ELECTRICAL CIRCUITS) VOLTAGE AND CURRENT

2.1 INTRODUCTION

Nearly every day the word voltage is encountered. In our flashlights, we have all replaced batteries that had different voltage levels, answering machines, calculators, bikes, and so on. It is quite common knowledge that current is something that passes through the wires and creates sparks and probably fire when there is a "short circuit." Current rent heats up the coils of an electric heater or the range of an electric heater; this produces light when moving through a bulb's filament; it causes twists and kinks in an electric iron wire over time, and so on. This chapter describes and explores in some detail the basic influence of current and voltage and the properties of each. Hopefully, any mysteries surrounding each one's general features will be eliminated, and you will gain a clear understanding of each one's impact on an electrical / electronic circuit.

2.2 ATOMS AND THEIR STRUCTURE A fundamental understanding of current and voltage concepts requires a certain degree of familiarity with the atom and its structure. The simplest of all atoms is the hydrogen atom, made up of two basic particles, the proton and the electron,

2.3 VOLTAGE The number of protons in the nucleus exceeds the number of orbiting electrons by 1 for the area within the dashed boundary, so that the net charge is positive. Charge is measured in coulombs, the energy in joules, and the voltage in volts. To find energy W = QV

To find charge Q ¿

W V

2.4 CURRENT The applied voltage is the starting mechanism the current is a reaction to the applied voltage. The unit of current measurement, ampere. Using the coulomb as the unit of charge, the current in amperes can be determined using. I amperes (A), Q coulombs (C), t time (s). Q I ¿ t Other configurations Q = It

Q t ¿ I

2.5 VOLTAGE SOURCES The term dc, used throughout this text, is an abbreviation for direct current, which encompasses all systems where there is a unidirectional (one direction) flow of charge. DC voltage sources can usually be categorized into three basic types: Batteries , generators, and power supplies.

2.10 AMMETERS AND VOLTMETERS It is important to be able to measure the current and voltage levels of the electrical operating system in order to check its operation, isolate malfunctions and investigate the effects that cannot be predicted on paper. Ammeters are used to measure current levels, as the names imply; voltmeters, the potential difference between two points....