McGraw-Hill © 2013 The McGraw-Hill Companies Inc. All rights reserved. Electricity Principles & Applications Eighth Edition Chapter 3 Basic Circuits,

McGraw-Hill © 2013 The McGraw-Hill Companies Inc. All rights reserved.

ElectricityElectricity

Principles & ApplicationsPrinciples & ApplicationsEighth EditionEighth Edition

Chapter 3Basic Circuits, Laws,and Measurements(student version)

Richard J. Fowler


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INTRODUCTION

• Circuit Symbols (p 46)

• Circuit Diagrams (p 45)

• Parts of a Circuit (p 45)

• Measuring Electrical Quantities (p 53)

• Calculating Electrical Quantities (p 47)

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Dear Student:

This presentation is arranged in segments. Each segmentis preceded by a Concept Preview slide and is followed by aConcept Review slide. When you reach a Concept Reviewslide, you can return to the beginning of that segment byclicking on the Repeat Segment button. This will allow youto view that segment again, if you want to.

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Concept Preview• Electrical components can be

represented by schematic symbols.• A complete circuit needs a power source,

a load, conductors, and insulation.

• A schematic diagram doesn’t show thephysical layout of the components.

• Insulation, although required, isn’t shown on a schematic diagram.

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+ Terminal

DeviceSymbol

Symbols and Components

Symbol Device

Cell(p 46)

Resistor(p 43+)

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This complete circuit uses the following: •An energy or power source

•A control device

•A load

•Conductors •Insulation (not shown)

(p 45)

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Cell

mA 2

V

DC

AC

20

200

2k

20K

V- COM mA

1.52

V

Select and arrange the components.Connect a wire from: 1) the cell to the switch, 2) the switch to the light, and 3) the light to the cell.

Connect the meter, and flip the switch.

Constructing and Checking a Lamp Circuit(p 58)

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Circuit QuizAn electrical component has a ____ as well as a name.

The long bar on the cell symbol isthe ____ terminal of the cell.

A complete circuit has a ____ ____ that forces current to flow.

A complete circuit often has a ____ ____ that turns the circuit off and on.

A complete circuit has a ____ thatcontrols the current flow.

A complete circuit has ____ thatroute the current .

symbol

positive

power source

control device

load

conductors

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Concept Review• Electrical components can be

represented by schematic symbols.• A complete circuit needs a power source,

a load, conductors, and insulation.

• A schematic diagram doesn’t show thephysical layout of the components.

• Insulation, although required, isn’t shown on a schematic diagram.

Repeat Segment

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Concept Preview• Select the correct function on a

meter before making a measurement.

• Interrupt the circuit to measure current.

• Remove power from the circuitbefore measuring resistance.

• Observe polarity when measuring current or voltage.

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k mAmV V A

+ V A COM - d c a c

MEASURING VOLTAGE

Select the dcVfunction

Connect - lead to - terminal of source

Connect + lead to + terminal of source

R1

1 k

S1

SPSTB1

15 V

(p 58)

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k mAmV V A

+ V A COM - d c a c

Select the dc mA function

R1

1 k

S1

SPSTB1

15 V

MEASURING CURRENT(p 59)

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R1

1 k

S1

SPSTB1

15 V

k mAmV V A

+ V A COM - d c a c

Select the dc mA function

Physicallyinterrupt thecircuit

Connect the - lead so

that electrons enter it

Connect the + lead to the other point

MEASURING CURRENT(p 59)

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MEASURING RESISTANCE

k mAmV V A

+ V A COM - d c a c

Select the kfunction

R1

1 k

S1

SPSTB1

15 V

(p 57)

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k mAmV V A

+ V A COM - d c a c

Select the kfunction

R1

1 k

S1

SPSTB1

15 V

Remove power(open switch)

Connect the leads

MEASURING RESISTANCE(p 57)

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Measurement QuizSelect the correct ____ of the meter before measuring an electrical quantity.

When measuring voltage, the meter’s positive leadis connected to the ____ terminal of the source.

When measuring current, the meter’s ____ leadreceives electrons from the circuit.

When measuring ____ , the meter is connected tothe points created by interrupting the circuit.

Power is removed from the circuit beforemeasuring ____.

function

positive

negative

current

resistance

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Concept Review• Select the correct function on a

meter before making a measurement.

• Interrupt the circuit to measure current.

• Remove power from the circuitbefore measuring resistance.

• Observe polarity when measuring current or voltage.

Repeat Segment

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Concept Preview• Ohm’s law states that I = V/R.

• Rearrangement can yield V = IR.

• Rearrangement also yields R = V/I.

• Any of three formulae can be used to calculate power.

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CALCULATING CURRENT

I =VR

= 36 V1800

= 0.02 A = 20 mA

S1

SPST

R

1.8 k

B1

36 V

(p 48)

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CALCULATING RESISTANCE

R = V I =

24 V 0.03 A

= 800 = 0.8 k

R

B1

24 V

A0.03 A

(p 49)

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CALCULATING VOLTAGE

V = IR = 0.15 A x 270 = 40.5 V

R

B1

A0.15 A

(p 49)

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CALCULATING POWER

P =

0.2 A

IV = 0.2 A x 54 V= 10.8 W

V54 V

P = I2R = 0.2 A x 0.2 A x 270 = 10.8 W

P = V2/R = (54 V x 54 V) / 270 = 10.8 W

A(p 49)

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Calculation QuizDetermine I when R = 10 and V = 25 V.

Determine R when I = 1.3 A and V = 26 V.

Determine V when R = 15 and I = 1.2 A.

Determine P when I = 3.3 A and V = 16 V.

Determine P when I = 4 A and R = 20 .

Determine P when V = 8 V and R = 16 .

2.5 A

20

18 V

52.8 W

320 W

4 W

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Concept Review• Ohm’s law states that I = V/R.

• Rearrangement can yield V = IR.

• Rearrangement also yields R = V/I.

• Any of three formulae can be used to calculate power.

Repeat Segment

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REVIEW• Circuit Symbols• Circuit Diagrams• Parts of a Circuit• Measuring Electrical Quantities• Calculating Electrical Quantities

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McGraw-Hill © 2013 The McGraw-Hill Companies Inc. All rights reserved. Electricity Principles & Applications Eighth Edition Chapter 3 Basic Circuits,