# Electrical Technology

**Topics:**Electric current, Electrical resistance, Electrical impedance

**Pages:**40 (9993 words)

**Published:**December 20, 2012

Objective – Chapter 11

1.0 INTRODUCTION TO ELECTRICAL CIRCUITS2

Basic Quantities and Units in Electrical2

Quantities2

Units3

Factors Affecting Resistance4

Length of the Conductor:4

Area of Cross-Section of the Conductor:4

Electrical Resistivity of Substances5

Effect of Temperature5

Components of Electrical Circuits6

Components of an Electric Circuit7

Measuring Current, Voltage and Resistance8

Measuring voltage8

Measuring current9

Measuring resistance9

Ohm's Law, Electricity10

Definition of Ohm11

Unit of resistance is 'ohm'11

Statement of Ohm's Law11

Ohm’s law : Current13

Ohm’s Law : Voltage13

Ohm’s Law : Resistance13

Ohm’s Law : Formula Transformation14

Electric Power and Its Derivation15

DC POWER: DC Power V and I.15

Problems - Electrical Power16

Answers to Problems - Electrical Power16

Electricity Unit Measure (Electrical energy)17

Heating effect of electricity17

SERIES AND PARALLEL RESISTORS:17

Series Resistors.18

Two Resistors in Parallel.18

Three or more Resistors in Parallel.19

SERIES / PARALLEL RESISTORS:19

DC VOLTAGE: Voltage Divider.21

DC VOLTAGE: Loading a Voltage Divider.21

Problems - The Potential Divider22

Answers to Problems - The Potential Divider23

DC CURRENT: Current Divider.24

Problems - The Current Divider25

Answers to Problems - The Current Divider25

Kirchhoff's Laws26

Kirchhoff's Current Law27

The algebraic sum of current into any junction is zero.27

Kirchhoff's Current Law in action27

i2 + i3 = i1 + i427

Kirchhoff's Voltage Law28

Positive and Negative Signs in Kirchhoff's Voltage Law28

Kirchhoff's Voltage Law in action28

Problems - Kirchoff's Laws30

Answers to Problems - Kirchoff's Laws31

Exercise33

CHAPTER 237

37

INDUCTOR, CAPACITOR AND ALTERNATING CURRENT37

Objective – Chapter 237

INDUCTOR38

Basic principles of inductors38

Inductance39

Principles of Electromagnetic Induction39

SELF-INDUCTION40

Inductive reactance (XL ) and the factors affecting inductive reactance40

Inductors In Series.41

Inductors in Parallel.41

Storing Energy in an Inductor.42

Capacitor43

Basic principles of capacitors43

Units of Capacitance44

PARALLEL PLATE CAPACITOR44

Parallel Capacitors44

Series Capacitors45

Effects of capacitors in electrical circuits47

Energy Storage47

Alternating Current Circuits48

AC basic circuits characteristic48

AC THEORY: AC Ohm's Law.48

AC THEORY: Voltage and Current for R.49

AC THEORY: Voltage and Current for C.49

AC THEORY: Voltage and Current for L.50

AC VOLTAGE AND CURRENT: Resistor, Voltage and Current Relationship.50

AC VOLTAGE AND CURRENT: Capacitor, Voltage and Current Relationship.51

AC VOLTAGE AND CURRENT: Inductor, Voltage and Current Relationship.52

AC VOLTAGE AND CURRENT: Series RCL Voltage Current Relationships52

AC VOLTAGE AND CURRENT: Angle of Rotation.53

THREE PHASE SYSTEM55

THREE PHASE SYSTEM (3)55

Simple three phase transmission57

Differentiate between three phase system and single phase system58

Objective – Chapter 1

Upon completion of this topic, student should be able to:

* Classify basic electrical Quantities (units and symbols) * Classify types of electrical circuits

* Classify Ohm’s Law

* Classify Electrical Power

* Classify Electrical Energy

* Classify the characteristic of series and parallel circuits * Explain Kirchhoff’s Law in complex electrical circuits

1.0 INTRODUCTION TO ELECTRICAL CIRCUITS

Basic Quantities and Units in Electrical

Quantities

The table shows electrical quantities which are used in electronics. The relationship between quantities can be written using words or symbols (letters), but symbols are normally used because they are much shorter; for example V is used for voltage, I for current and R for resistance: As a...

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