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SECOND EDITION

Second Printing, June 2003

Copyright February, 2003 Lab-Volt Systems, Inc.

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i

Table of Contents

Section 1 – Workstation Inventory and Installation............................................................... 1-1

Inventory of Workstation ........................................................................................................ 1-1

Minimum Computer Requirements.................................................................................... 1-1

Equipment and Supplies..................................................................................................... 1-1

Equipment Installation ............................................................................................................ 1-1

Software Installation ............................................................................................................... 1-1

Section 2 – Introduction to F.A.C.E.T. Curriculum............................................................... 2-1

Getting Started ........................................................................................................................ 2-2

Screen Buttons ........................................................................................................................ 2-3

F.A.C.E.T. Help Screens and Resources................................................................................. 2-4

Internet Access ........................................................................................................................ 2-5

Instructor Annotation Tool...................................................................................................... 2-5

Student Journal........................................................................................................................ 2-5

Assessing Progress .................................................................................................................. 2-6

Real-Number Questions and Answers .................................................................................... 2-8

Safety .................................................................................................................................... 2-11

Section 3 – Courseware ............................................................................................................. 3-1

Unit 1 – Trainer Familiarization .............................................................................................. 3-1

Exercise 1 – Instrument Familiarization ................................................................................. 3-2

Exercise 2 – F.A.C.E.T. Base Unit Familiarization ................................................................ 3-5

Exercise 3 – DC Board Familiarization .................................................................................. 3-8

Unit 2 – Safety .......................................................................................................................... 3-13

Exercise 1 – Basic Safety Rules............................................................................................ 3-14

Exercise 2 – Electrical Safety Rules ..................................................................................... 3-16

Unit 3 – Electronic Quantities................................................................................................. 3-21

Exercise 1 – Circuit Voltages................................................................................................ 3-23

Exercise 2 – Circuit Current.................................................................................................. 3-26

Exercise 3 – Circuit Resistance............................................................................................. 3-29

Unit 4 – DC Power Sources ..................................................................................................... 3-35

Exercise 1 – Series and Parallel Battery Circuits.................................................................. 3-37

Exercise 2 – Series-Opposing DC Sources ........................................................................... 3-42

ii

Unit 5 – Switches and Switching Concepts ............................................................................ 3-49

Exercise 1 – Identify Types of Switches............................................................................... 3-51

Exercise 2 – Switching Concepts.......................................................................................... 3-56

Unit 6 – Ohm's Law ................................................................................................................. 3-63

Exercise 1 – Ohm's Law - Circuit Resistance ....................................................................... 3-64

Exercise 2 – Ohm's Law - Circuit Current ............................................................................ 3-71

Exercise 3 – Ohm's Law - Circuit Voltage ........................................................................... 3-76

Unit 7 – Series Resistive Circuits............................................................................................ 3-85

Exercise 1 – Resistance in a Series Resistive Circuit ........................................................... 3-87

Exercise 2 – Current in a Series Resistive Circuit ................................................................ 3-92

Exercise 3 – Voltage in a Series Resistive Circuit................................................................ 3-97

Unit 8 – Parallel Resistive Circuits....................................................................................... 3-107

Exercise 1 – Resistance in a Parallel Circuit....................................................................... 3-109

Exercise 2 – Voltage/Current in a Parallel Circuit.............................................................. 3-113

Unit 9 – Series/Parallel Resistive Circuits ........................................................................... 3-123

Exercise 1 – Resistance in a Series/Parallel Circuit............................................................ 3-125

Exercise 2 – Voltage in a Series/Parallel Circuit ................................................................ 3-130

Exercise 3 – Current in a Series/Parallel Circuit................................................................. 3-135

Unit 10 – Power in DC Circuits ............................................................................................ 3-143

Exercise 1 – Power in a Series Resistive Circuit ................................................................ 3-144

Exercise 2 – Power in a Parallel Resistive Circuit .............................................................. 3-148

Exercise 3 – Power in a Series/Parallel Circuit................................................................... 3-152

Unit 11 – Potentiometers and Rheostats .............................................................................. 3-163

Exercise 1 – The Rheostat................................................................................................... 3-164

Exercise 2 – The Potentiometer .......................................................................................... 3-170

Unit 12 – Voltage and Current Divider Circuits................................................................. 3-177

Exercise 1 – Voltage Dividers............................................................................................. 3-178

Exercise 2 – Current Dividers ............................................................................................. 3-182

Exercise 3 – Loading Voltage/Current Dividers................................................................. 3-186

Unit 13 – Direct Current Meters .......................................................................................... 3-193

Exercise 1 – The DC Ammeter ........................................................................................... 3-194

Exercise 2 – The DC Ohmmeter ......................................................................................... 3-198

Exercise 3 – The DC Voltmeter .......................................................................................... 3-201

iii

Appendix A – Pretest and Posttest Questions and Answers ................................................. A-1

Pretest Questions.................................................................................................................... A-1

Posttest Questions .................................................................................................................. A-9

Appendix B – Faults and Circuit Modifications (CMs) .........................................................B-1

Appendix C – Board and Courseware Troubleshooting....................................................... C-1

iv

THIS

v

Introduction

This Instructor Guide is divided into three sections and the appendices. It provides a unit-by-unit

outline of the Fault Assisted Circuits for Electronics Training (F.A.C.E.T.) curriculum.

Section 1 – Workstation Inventory and Installation contains a list and description of

equipment and materials required for all units in this course of study as well as installation

instructions.

Section 2 – Introduction to F.A.C.E.T. Curriculum provides a description of the courseware

structure, instructions on getting started with the multimedia presentation, and an explanation of

student-progress assessment methods.

Section 3 – Courseware includes information that enables the instructor to gain a general

understanding of the units within the course.

♦ The unit objective

♦ Unit Fundamentals questions and answers

♦ A list of new terms and words for the unit

♦ Equipment required for the unit

♦ The exercise objectives

♦ Exercise Discussion questions and answers

♦ Exercise Procedure questions and answers

♦ Review questions and answers

♦ CMs and Faults available

♦ Unit Test questions and answers

♦ Troubleshooting questions and answers (where applicable)

Appendices include the questions and answers to the Pretest and Posttest plus additional specific

information on faults and circuit modifications (CMs).

Please complete and return the OWNER REGISTRATION CARD included with the CD-

ROM. This will assist Lab-Volt in ensuring that our customers receive maximum support.

vi

THIS

SECTION 1 – WORKSTATION INVENTORY

AND INSTALLATION

DC Fundamentals Section 1 – Workstation Inventory and Installation

1-1

SECTION 1 – WORKSTATION INVENTORY AND INSTALLATION

Inventory of Workstation

Use this section to identify and inventory the items needed.

Minimum Computer Requirements 100% compatible Windows

®PC with Windows98 second edition or newer, NT, 2000, Me or XP;

Pentium class CPU, (Pentium II or newer); 126 MB RAM; 10 GB HDD; CD-ROM drive; SVGA

monitor and video card capable of 32-bit color display at 1024 x 768 resolution and sound

capabilities.

Equipment and Supplies The following equipment and supplies are needed for DC Fundamentals:

Quantity Description

1 F.A.C.E.T. base unit

1 DC FUNDAMENTALS circuit board

1 Multimeter

1 Student Workbook

1 Instructor Guide

Equipment Installation

To install the hardware, refer to the Tech-Lab (minimum version 6.x) Installation Guide.

Software Installation

Third Party Application Installation

All applications and files that the courseware launches, or that are required for the course should

be installed before the courseware. Load all third party software according to the manufacturers'

directions. Install this software to the default location and note that location. (Alternatively, you

can install this software to a different location that you designate.) Remember to register all

software as required.

No third-party software is required for this course.

Installation of Courseware and Resources

To install the courseware and resources, refer to the Tech-Lab (minimum version 6.x) and

Gradepoint 2020 (minimum version 6.x) Installation Guide.

DC Fundamentals Section 1 – Workstation Inventory and Installation

1-2

SECTION 2 – INTRODUCTION TO F.A.C.E.T.

CURRICULUM

DC Fundamentals Section 2 – Introduction to F.A.C.E.T. Curriculum

2-1

SECTION 2 – INTRODUCTION TO F.A.C.E.T. CURRICULUM

Overview F.A.C.E.T. curriculum is multimedia-based courseware. The curriculum gives students hands-on

experience using equipment and software closely associated with industry standards. It provides

students with opportunities for instruction in academic and technical skills.

All courses are activity-driven curricula. Each course consists of several units containing two or

more exercises. Each unit begins with a statement explaining the overall goal of the unit (Unit

Objective). This is followed by Unit Fundamentals. Next is a list of new terms and words then

the equipment required for the unit. The exercises follow the unit material. When students

complete all the exercises, they complete the Troubleshooting section and take the Unit Test.

The exercises consist of an exercise objective, exercise discussion, and exercise procedures. The

Exercise Conclusions section provides the students with a list of their achievements. Every

exercise concludes with Review Questions. Available circuit modifications (CMs) and faults are

listed after the review questions. Additional specific information on CMs and faults is available

in Appendix B.


2-2

Getting Started

Desktop

After the Tech-Lab System is installed, the TechLab icon appears on the desktop.

1. Click on the TechLab icon.

2. The student clicks on LOGON and selects his or her name.

3. The student enters his or her password and clicks on OK. (If he or she is creating a password,

four alphanumeric characters must be entered. The system will ask for the password to be

entered again for verification. Keep a record of the students' passwords.)

4. The previous two steps are repeated until all members of the student team have logged on.

Click on Complete and then Yes.

5. When the Available Courses menu appears, students click on the course name.

6. A window with the name of the course and a list of units for that course appears. Students

click on the unit name. The unit title page appears and the students are ready to begin.

Selecting Other Courses and Exiting the Courseware

1. Clicking on Exit when in a unit returns the student to the list of units for that course.

2. If students wish to select another unit, they click on it.

3. If students wish to exit F.A.C.E.T., they click on the X symbol in the upper right corner.

4. If students wish to select another course, they click on the Course Menu button. The

Available Courses menu screen appear. They may also exit F.A.C.E.T. from this screen by

clicking on the LOGOFF button.


2-3

Screen Buttons

If you click on the F.A.C.E.T. logo on the top right of the unit title page the About screen

appears. It acknowledges the copyright holder(s) of video and/or screen-capture material used in

the topic.

The Menu button calls these menus:

when on an exercise menu screen, it calls the Unit Menu.

when on an exercise screen, it calls the Exercise Menu.

when on a unit screen, it calls the Unit Menu.

The Bookmark button marks the current screen. A student can click on the button at any time in

the lesson. The second time the student clicks on the button, the page displayed when the button

was first clicked will return to the screen. Any bookmarks used during a lesson are not saved

when the student logs out of the lesson.

The Application Launch button opens third-party software.

Click on the Resources button to view a pop-up menu. The pop-up menu includes access to a

calculator, a student journal, new terms and words, a print current screen option, the Lab-Volt

authored Internet Website, and a variety of F.A.C.E.T. help screens.

The Help button aids students with system information. On certain screens the Help button

appears to be depressed. On these screens, clicking on the Help button will access Screen Help

windows (context-sensitive help).

The Internet button opens an Internet browser. Students will have unrestricted access to all

search engines and web sites unless the school administration has restricted this usage.

Use the Exit button to exit the course.

The right arrow ⇒ button moves you forward to the next screen.

The left arrow ⇐ button moves you backward to the previous screen.


2-4

F.A.C.E.T. Help Screens and Resources

There are three ways to access F.A.C.E.T. help screens and other resources.

System Help Students access System Help by clicking on the Help button at the bottom of the screen when the

button does not appear to be depressed. The menu selections access a variety of system help,

navigation, and information windows.

Screen Help On certain screens, the Help button appears to be depressed. On these screens, clicking on the

Help button will access Screen Help windows. This is information specific to the content of that

particular screen.

Resources Students click on the Resources button to access the following windows.

Calculator

F.A.C.E.T. 32-Bit Microprocessor Help

F.A.C.E.T. Analog Communications Setup Procedure

F.A.C.E.T. Digital Communications Help

F.A.C.E.T. Electronics and Troubleshooting Help

F.A.C.E.T. Fiber Optic Communications Help

F.A.C.E.T. Math Help

Internet Link

New Terms and Words

Print Current Page

Student Journal


2-5

Internet Access

There are two ways for students to access the Internet:

The Internet button opens an Internet browser. Students have unrestricted access to all search

engines and websites unless the school administration has restricted this usage.

The Resources button pops up a menu that includes access to the Lab-Volt

authored Internet website. If students wish to access this site when they are not in

the lesson, then they must go to http://learning.labvolt.com.

NOTE: The Lab-Volt Internet site does not have content-filtering

software to block access to objectionable or inappropriate

websites.

Instructor Annotation Tool

The annotation tool gives the instructor the ability to add comments or additional information

onscreen. Refer to the Tech-Lab and GradePoint 2020 Installation Guide for detailed

information.

Student Journal

The student journal is an online notebook that each student can access while they are logged into

TechLab. The journal allows students to share notes with other students in their workgroups.

When used in conjunction with GradePoint 2020, the instructor may post messages, review, edit,

or delete any journal note.


2-6

Assessing Progress

Assessment Tools

Student assessment is achieved in several ways:

♦ Exercise questions

♦ Unit tests

♦ Pretest and Posttest

♦ Troubleshooting questions

Exercise and Troubleshooting Questions

Throughout the unit material, exercise discussion, exercise procedure, and troubleshooting

sections there are several types of questions with instant feedback. These questions occur in the

following formats:

♦ Multiple choice

♦ True-false

♦ Real-number entry

In most cases, when your students encounter a question set, they must answer these questions

before continuing. However, there are cases where students may progress to the next screen

without answering the questions. Lab-Volt recommends that you encourage your students to

complete all questions. In this way, students reinforce the material that's presented, verify that

they understand this material, and are empowered to decide if a review of this material is

required.

Review Questions

At the end of each exercise, there are review questions. The student receives feedback with each

entry. Feedback guides the student toward the correct answer.

Unit Tests

A unit test appears at the end of each unit. The test consists of 10 multiple-choice questions with

the option of having feedback. The Tech-Lab System defaults to no feedback, but the instructor

can configure the test so that students receive feedback after taking the test. You can randomize

questions in the unit test. Use the Tech-Lab Global Configurator to make feedback available,

randomize questions, and select other configuration options if desired. Refer to the Tech Lab

Quick-Start Guide for detailed information.


2-7

Pretest and Posttest

Every course includes a pretest and a posttest. These are multiple choice tests. Refer to the Tech

Lab Quick-Start Guide for detailed information on how to record student competency gains.

Grading

Student grades are based on exercise questions, troubleshooting questions, a unit test, and a

posttest. The default weighting value of the unit test and the threshold for passing the unit test

can be adjusted by using the Global Configurator of the Tech-Lab System. Refer to the Tech Lab

Quick-Start Guide for detailed information.

Student Progress and Instructor Feedback

Unit progress is available through the Unit menu. The Progress window allows the instructor and

student to view the percentage of the unit completed, number of sessions, and time spent on that

unit. The Progress window shows whether the Unit Test was completed. If the test was

completed, it indicates whether the student passed based on the scoring criteria.


2-8

Real-Number Questions and Answers

Throughout F.A.C.E.T. courses students may encounter real-number questions such as the one

shown below. Answers to real-number questions are graded correct if they fall within an

acceptable tolerance range.

The answer to the question posed in the illustration above does not involve a recall value from a

previous question. It appears in the Instructor Guide (IG) as shown in the box below.

The information in the IG tells you where the question is located and the range of acceptable

answers. In this case, the acceptable answers fall within the range of the nominal answer plus or

minus 5 percent tolerance: (15 ± 5%).

Location: Exercise Procedure page:

se1p1, Question ID: e1p1a

VS = Vdc

Recall Label for this Question: V1

Nominal Answer: 15.0

Min/Max Value: (14.25) to (15.75)

Value Calculation: 15.000

Correct Tolerance Percent = true

Correct Minus Tolerance = 5

Correct Plus Tolerance = 5

This is the name the computer uses internally

to identify the input value. In this case, 14.5

will be stored under the name V1.

NOTE: The recall value V1 is not the same as

the voltage V1. The recall label does not

appear onscreen.

In this case, the answer to this question is not

based on a value recalled from a previous

question. Therefore, the Value Calculation is

equal to the Nominal Answer.

The word "true" tells you that the tolerance is

calculated as a percent.

e1p1 stands for

Exercise 1 Procedure screen 1

The computer

saves this input

value so that it can

be recalled for use

in later questions.


2-9

A second example (shown below) illustrates an answer that the computer grades using a value

recalled from a previous question.

When a real-number question is based on a recall value from a previous question, the Min/Max

Value shown in the Instructor Guide is based upon a calculation using the lowest and highest

possible recall value. It represents the theoretical range of answers that could be accepted by the

computer. (It is not the nominal answer plus or minus the tolerance.)

To find the actual range of answers that the computer will accept onscreen, you must use the

actual recall value (14.5 in this example) in your calculations; see below.

NOTE: After four incorrect answers, students will be prompted to press <Ins> to insert the

correct answer if this feature has been enabled in the configuration settings. When the question is

based on a value recalled from a previous question, answers obtained using the Insert key may

not match the nominal answers in this guide.

Location: Exercise Procedure page:

se1p5, Question ID: e1p5c

IT = mA

Recall Label for this Question: I1

Nominal Answer: 9.091 *Min/Max Value: (6.477) to (11.93)

Value Calculation: #V1#/1650*1000




Since the value for #V1# is 14.5, the

computer will accept answers in the

following range as correct:

14.5/1650*1000 ± 25% or

8.79 ± 25% or

6.59 to 10.99

This calculated range is different from the

Min/Max Value shown in the IG, which

was based upon a calculation using the

lowest and highest possible recall value.

Any letter enclosed in "#" signs refers to a

recall value from a previous question.


2-10

Recall Values in Text

Sometimes numbers displayed on screen are values recalled from input on previous screens.

Because these numbers are recall values, they will change for each student.

The Instructor Guide lists the recall label in place of a number in this question.

The value of 10

was recalled

from a previous

screen.

Location:Exercise Procedure page: se1p11, Question ID: e1p11c

IR2 = VR2/R2

= #V4#/3.3 kΩ

= mA

Recall Label for this Question: I1


Min/Max Value: (2.489) to (3.164)

Value Calculation: #V4#/3.3




This is a

recall label

for a value

recorded in a

previous

question.

The correct

answer will

depend on the

value the student

recorded in the

previous question.


2-11

Safety

Safety is everyone’s responsibility. All must cooperate to create the safest possible working

environment. Students must be reminded of the potential for harm, given common sense safety

rules, and instructed to follow the electrical safety rules.

Any environment can be hazardous when it is unfamiliar. The F.A.C.E.T. computer-based

laboratory may be a new environment to some students. Instruct students in the proper use of the

F.A.C.E.T. equipment and explain what behavior is expected of them in this laboratory. It is up

to the instructor to provide the necessary introduction to the learning environment and the

equipment. This task will prevent injury to both student and equipment.

The voltage and current used in the F.A.C.E.T. Computer-Based Laboratory are, in themselves,

harmless to the normal, healthy person. However, an electrical shock coming as a surprise will

be uncomfortable and may cause a reaction that could create injury. The students should be made

aware of the following electrical safety rules.

1. Turn off the power before working on a circuit.

2. Always confirm that the circuit is wired correctly before turning on the power. If required,

have your instructor check your circuit wiring.

3. Perform the experiments as you are instructed: do not deviate from the documentation.

4. Never touch “live” wires with your bare hands or with tools.

5. Always hold test leads by their insulated areas.

6. Be aware that some components can become very hot during operation. (However, this is not

a normal condition for your F.A.C.E.T. course equipment.) Always allow time for the

components to cool before proceeding to touch or remove them from the circuit.

7. Do not work without supervision. Be sure someone is nearby to shut off the power and

provide first aid in case of an accident.

8. Remove power cords by the plug, not by pulling on the cord. Check for cracked or broken

insulation on the cord.


2-12

SECTION 3 – COURSEWARE

SECTION 3 – COURSEWARE

DC Fundamentals Unit 1 – Trainer Familiarization

3-1

UNIT 1 – TRAINER FAMILIARIZATION

UNIT OBJECTIVE Set up the F.A.C.E.T. system by using standard lab procedures.

UNIT FUNDAMENTALS

Location: Unit Fundamentals page: sf6, Question ID: f6a

Your circuit board is inserted into or removed from the base unit after the ZIF connector is

a. opened.

b. closed.

c. opened or closed, provided you apply sufficient force.

CMS AVAILABLE

None

FAULTS AVAILABLE

None

NEW TERMS AND WORDS

dc circuits – direct current circuits; a flow of electrons in one direction along an electrical path.

circuits – paths for current to flow.

circuit board – specially constructed board containing many electrical circuits.

power sources – devices that supply electricity to an electrical circuit; also called power

supplies.

cells – basic sources of power that produce electricity through chemical action.

schematic – drawing that uses standard symbols to show electrical paths and components.

symbol – a simple representative drawing of a component.

crowbar – a circuit that rapidly shorts the output voltage to ground.

EQUIPMENT REQUIRED

F.A.C.E.T. base unit

DC FUNDAMENTALS circuit board

Multimeter


3-2

Exercise 1 – Instrument Familiarization

EXERCISE OBJECTIVE

Activate a power source on the F.A.C.E.T. system. Verify results by measuring the output

voltage of the power source with a multimeter.

EXERCISE DISCUSSION

Location: Exercise Discussion page: se1d5, Question ID: e1d5a

Typical analog and digital multimeters can measure

a. voltage.

b. current.

c. resistance.

d. All of the above.

EXERCISE PROCEDURE

Location: Exercise Procedure page: se1p4, Question ID: e1p4a

5. Based on your meter indication, what is the polarity of your power supply voltage?

a. negative (–)

b. positive (+)

c. The multimeter does not indicate a polarity.


7. Is the numerical value of your voltage reading on the multimeter affected by the test lead

placement?

a. No, the placement of the multimeter test leads does not alter the voltage indication.

b. Yes, the placement of the multimeter test leads alters the voltage indication.


8. Is the polarity indication of your meter affected by the test lead placement?

a. No, a change in polarity is not detected.

b. Yes, the negative (-) sign indicates that the multimeter polarity indication is affected by

test lead placement.


3-3


9. Should you be concerned with the expected polarity of a voltage reading before you connect

your multimeter into the circuit?

a. No, expected polarity is not important because a multimeter always provides some form of

polarity indication.

b. Yes, it is best to know what your polarity should be before you connect your multimeter

into the circuit.

REVIEW QUESTIONS

Location: Review Questions page: se1r1, Question ID: e1r1

1. This course of the F.A.C.E.T. system is made up of a

a. base unit.

b. base unit and DC FUNDAMENTALS circuit board.

c. base unit and several circuit boards.

d. base unit and AC FUNDAMENTALS circuit board.


2. Circuit modifications (CMs)

a. modify existing circuits on the circuit board.

b. insert modified circuits on the circuit board.

c. control the application of variable power supply voltages.

d. place loose components in the circuit.


3. When both LEDs on the base unit are on, it indicates that the

a. power switch is on.

b. circuit board is inserted into the base unit.

c. base unit is connected to one of the computer serial ports.

d. AC power cord is plugged in and the power switch is on.


4. A dc power supply can be

a. only positive.

b. only negative.

c. positive or negative depending on the common reference point.

d. a positive or negative supply as selected by the variable control.


3-4


5. The multimeter used with the F.A.C.E.T. program must be able to measure

a. analog signals.

b. digital signals.

c. current, resistance, and voltage.

d. analog, digital, and autorange.

CMS AVAILABLE

None

FAULTS AVAILABLE

None


3-5

Exercise 2 – F.A.C.E.T. Base Unit Familiarization

EXERCISE OBJECTIVE

Discover the operating features of the base unit and DC FUNDAMENTALS circuit board. You

will verify your results with an operational test.

EXERCISE DISCUSSION


One of the base unit LEDs is off (the other is on). This condition indicates

a. the base unit's power switch is off.

b. the circuit board is not inserted.

c. the wrong circuit board is inserted.

d. an overvoltage and/or short circuit condition on a circuit board.


To insert your circuit board into the base unit,

a. ensure that the ZIF connector is open.

b. ensure that the ZIF connector is closed.

c. use excessive force and don't check the position of the ZIF connector.


To remove your circuit board from the base unit,

a. ensure that the ZIF connector is open.

b. ensure that the ZIF connector is closed.

c. use excessive force and don't check the position of the ZIF connector.


Proper electrical connections between the base unit and a circuit board require that the ZIF

connector be

a. open.

b. closed.

c. either open or closed.


3-6

EXERCISE PROCEDURE


4. Which variable power supply control (s) do you use to initially adjust the OHM'S LAW circuit

block voltage?

a. the positive FINE base unit control.

b. the positive COURSE and FINE base unit controls.

c. the negative FINE base unit control.

d. the negative COURSE and FINE base units controls.


7. Which procedure allows you to set a circuit voltage precisely?

a. First set the FINE control to the approximate voltage. Then use the COARSE control to

determine the precise circuit voltage.

b. First set the COARSE control to the approximate voltage. Then use the FINE control to

determine the precise circuit voltage.

REVIEW QUESTIONS


1. To change the value of the positive power source in the OHM'S LAW circuit block from 6.00

Vdc to 6.08 Vdc, the

a. positive variable COURSE control is used.

b. positive variable COURSE and FINE controls are used.

c. positive variable FINE control is used.

d. positive power source cannot be changed.


2. The variable power source on the OHM'S LAW circuit block of the DC FUNDAMENTALS

circuit board is controlled by the

a. positive supply controls.

b. position of the ZIF connector.

c. negative supply controls.

d. by the resistor components R1 and R2.


3-7


3. To change the value of the positive power source in the OHM'S LAW circuit block form 2.0

Vdc to 8.47 Vdc, the

a. positive variable COURSE control is used.

b. positive variable COURSE and FINE controls are used.

c. positive variable FINE control is used.

d. positive source is variable only to 6.0 Vdc.


4. A circuit board is inserted into the base unit when the

a. base unit LEDs are on.

b. ZIF connector is closed.

c. ZIF connector knob is rotated CW.

d. ZIF connector knob is rotated CCW.


5. The variable power sources in the OHM'S LAW and BATTERIES circuit blocks read

approximately 0V and cannot be adjusted. You find that the cause is the

a. ZIF connector knob in the CCW position.

b. ZIF connector knob in the CW position.

c. position supply controls in the CCW position.

d. negative supply controls in the CCW position.

CMS AVAILABLE

CM 2

FAULTS AVAILABLE

FAULT 1


3-8

Exercise 3 – DC Board Familiarization

EXERCISE OBJECTIVE

Use specific trainer functions on the DC FUNDAMENTALS circuit board. Verify results with

voltage and current measurements.

EXERCISE DISCUSSION


Locate the SWITCHES circuit block on the DC FUNDAMENTALS circuit board. A two-post

connector inserted at the S1 test points a. completes both the S1 and S2 switch circuits.

b. completes only the S1 switch circuit.

c. does not complete any of the switch circuits.


Which circuit block uses potentiometers (variable resistors) to explore linear and nonlinear

relationships?

a. VOLTMETER/AMMETER/OHMMETER circuit block

b. POWER circuit block

c. LINEAR/NONLINEAR VARIABLE RESISTOR circuit block

EXERCISE PROCEDURE


2. Press switch S2. Is a two-post connector required to connect cell V4 into the S2 circuit?

a. no

b. yes


3. Connect the circuit shown. The two-post connector

a. completes the LED circuit.

b. powers the voltmeter.

c. breaks the LED circuit.


3-9


5. Based on your circuit observations, what is the relationship between the two-post connector,

the circuit, and the meter?

a. The two-post connector supplies power to both LEDs and to the voltmeter.

b. The two-post connector must be removed to complete the circuit, but it has no effect on

voltmeter operation.

c. The two-post connector completes the LED circuit, but it has no effect on voltmeter

operation.


8. Your circuit does not use a two-post connector, yet the LED brightness and meter readings

indicate a complete circuit. Why?

a. The ammeter takes the place of a two-post connector and breaks the circuit.

b. The ammeter takes the place of a two-post connector and makes the circuit.

c. The circuit is made because the dashed line that is silkscreened on your circuit indicates a

hardwired connection.

REVIEW QUESTIONS


1. The diagram of each circuit block on the DC FUNDAMENTALS circuit board is called a

a. symbol.

b. schematic.

c. circuit sketch.

d. line drawing.


2. The OHM'S LAW circuit block is used to

a. evaluate circuit quantities.

b. measure circuit voltages.

c. evaluate circuit operation.

d. measure circuit current.


3. The VOLTMETER/AMMETER/OHMMETER circuit block is used to

a. replace the multimeter with an analog meter.

b. explore the concept of variable voltage sources.

c. explore how a meter measures electronic quantities.

d. measure electronic quantities with a digital meter.


3-10


4. When you measure circuit current, the

a. multimeter is placed across the component.

b. circuit voltage flows through the multimeter.

c. circuit can never be completely energized.

d. circuit current flows through the multimeter.


5. In the F.A.C.E.T. program, current measurements will be mostly in what range?

a. ampere

b. milliampere

c. microampere

d. picoampere

CMS AVAILABLE

None

FAULTS AVAILABLE

None


3-11

UNIT TEST

Depending on configurator settings, these questions may be randomized onscreen.

Location: Unit Test Question page: sut1, Question ID: ut1

The F.A.C.E.T. base unit provides for protection against

a. overvoltage and power connection.

b. overvoltage, overcurrent, and reverse-power connection.

c. overcurrent and reverse-power connection.

d. overcurrent and power connection.


The parameters of circuit blocks can be altered by

a. inserting a fault via the base unit.

b. adjusting the variable power source.

c. inserting a circuit modification via the base unit.

d. inserting loose components into circuits at designated test points.


The DC FUNDAMENTALS circuit board is properly connected to the base unit when the

a. ZIF connector knob is fully CCW.

b. ZIF connector knob is fully CW.

c. ±15 Vdc power source is connected to the base unit.

d. power supply LEDs are illuminated.


The multimeter dc voltage function is selected by the

a. range switch.

b. automatic voltage selection circuit.

c. VOLTMETER circuit block on the DC FUNDAMENTALS circuit board.

d. person using the multimeter.


The variable power source in the OHM'S LAW circuit block on the DC FUNDAMENTALS

circuit board is adjusted by the

a. positive supply control on the base unit.

b. negative supply control on the base unit.

c. –15 Vdc control on the power supply.

d. +15 Vdc control on the power supply.


3-12


On the DC FUNDAMENTALS circuit board, test points separated by dashed lines are

a. used to measure voltage.

b. for inserting loose components.

c. used to energize the associated circuit.

d. for measuring the resistance of the circuit.


When measuring circuit current, the ammeter is connected

a. across the component.

b. to read a portion of the current.

c. so all circuit current flows through the ammeter.

d. parallel to the circuit to read all the circuit current.


The arrow through a battery symbol indicates

a. the direction of current flow.

b. the positive terminal.

c. the negative terminal.

d. a variable source output.


The symbol to the right represents a

a. zener diode.

b. light-emitting diode.

c. semiconductor diode.

d. solar cell.


The term milliampere is abbreviated

a. mA.

b. ma.

c. Ma.

d. mil.

DC Fundamentals Unit 2 – Safety

3-13

UNIT 2 – SAFETY

UNIT OBJECTIVE Identify safe working conditions in a typical electronic laboratory by using the illustrations and

information presented in this unit.

UNIT FUNDAMENTALS

No Questions

CMS AVAILABLE

None

FAULTS AVAILABLE

None

NEW TERMS AND WORDS

None

EQUIPMENT REQUIRED




3-14

Exercise 1 – Basic Safety Rules

EXERCISE OBJECTIVE

Employ safety in the workplace by using information and examples found in this exercise.

EXERCISE DISCUSSION

No Questions

EXERCISE PROCEDURE

No Questions

REVIEW QUESTIONS


1. One cause of shop accidents is

a. proper use of tools.

b. clean work areas.

c. talking while working.

d. wearing safety glasses.


2. Obeying safety rules is important in order to

a. prevent injury.

b. finish a job quickly.

c. lift heavy objects by yourself.

d. keep machines running between jobs.


3. When you need to use a power tool you should

a. borrow one from a fellow student.

b. get the instructor's approval first.

c. use any tool that is not being used.

d. use the tool when the instructor is not present.


3-15


4. While working in the shop, you see a fellow student cut his hand. The student should

a. continue working to finish his project.

b. cover the cut and continue working.

c. leave to get medical attention.

d. report the injury and get medical attention.


5. When working with a grinder, you should

a. turn it off when finished.

b. wear safety glasses.

c. keep the area clean.


CMS AVAILABLE

None

FAULTS AVAILABLE

None


3-16

Exercise 2 – Electrical Safety Rules

EXERCISE OBJECTIVE

Avoid electrical shock in the workplace by using information and examples found in this

exercise.

EXERCISE DISCUSSION

No Questions

EXERCISE PROCEDURE

No Questions

REVIEW QUESTIONS


1. When working with high-voltage circuits, you should

a. use only one hand.

b. work as quickly as possible.

c. have a fellow student make the measurements.

d. turn the power off.


2. You should discharge high-voltage capacitors before you work on a circuit because they

a. use excessive power.

b. are high-capacity components.

c. get hot when power is applied to them.

d. can hold an electrical charge.


3. To be sure that power is removed from a circuit, you should

a. turn the power switch to the OFF position.

b. check the circuit with a meter.

c. have a friend check that the power switch is in the OFF position.

d. remove the circuit from the equipment.


3-17


4. Another person should be in the laboratory with you to

a. help repair the equipment.

b. answer any questions you may have.

c. check your work.

d. help in case of an accident.


5. One source of accidents is

a. circuits with capacitors.

b. your using insulated test leads to check circuits.

c. cracked or broken insulation on cords.

d. your using only one hand when working with high voltage.

CMS AVAILABLE

None

FAULTS AVAILABLE

None


3-18

UNIT TEST



Clowning around in the laboratory can cause which of the following?

a. electrical shock

b. burns

c. cuts and bruises



Why is it important to have permission to use a power tool for the first time?

a. Power tools cost a lot.

b. There may be other people in the shop working.

c. The instructor can give you safety precautions.

d. Someone else may want to use it.


Removing a line cord by the plug ensures

a. a longer life for the line cord.

b. that the plug will not break.

c. that the line cord will break.

d. your receiving an electrical shock.


When two parts of your body touch an energized electrical circuit, the effect you may feel is

called

a. an electrical short.

b. an electrical shock.

c. a burning sensation.

d. a bad short circuit.


Someone should be nearby when you work on electrical circuits to

a. keep you company.

b. shut off power and give first aid in case of an accident.

c. show you how to repair faulty equipment if you have a problem.

d. help the instructor with the rest of the class.


3-19


You should never touch live wires with your bare hands because you

a. may break the wires.

b. may damage the circuit.

c. can get an electric shock.

d. can lower circuit resistance.


It is not a good idea to talk to someone operating electrical equipment because you

a. might damage the equipment.

b. could ruin an electronic device.

c. both may be injured.

d. may not get your work done.


The proper way to lift a heavy object is to

a. bend your knees, grasp the object, raise yourself and the object by straightening your

legs.

b. bend at the waist, grasp the object, raise yourself and the object by straightening your waist.

c. let your back and arms do all the work.

d. let your back do all the work.


After shutting off a machine, you should

a. start to clean up the area.

b. stay with the machine until it has completely stopped.

c. return all tools to the tool room.

d. have your instructor check your work area.


Safety rules should be obeyed in order to

a. finish the project as quickly as possible.

b. keep other students busy.

c. prevent injury to yourself and others.



3-20

DC Fundamentals Unit 3 – Electronic Quantities

3-21

UNIT 3 – ELECTRONIC QUANTITIES

UNIT OBJECTIVE Describe voltage, current, and resistance by using simple electronic circuits.

UNIT FUNDAMENTALS


An atom is made up of protons, electrons, and neutrons. Protons and electrons posses

a. positive charges.

b. positive and negative charges, respectively.

c. negative charges.

CMS AVAILABLE

None

FAULTS AVAILABLE

None

NEW TERMS AND WORDS

charge – a type of electric energy. The basic electric charges are the negative charge of the

electron and the positive charge of the proton.

atom – a basic building block of nature consisting of electrons, protons, and neutrons. Each

element in the universe is formed from its own type of atom. There are over one hundred

different types of atoms.

protons – positively charged subatomic particle.

electrons – negatively charged subatomic particles.

neutrons – subatomic particles that possess a neutral charge.

coulomb – the unit of measure for charge (equal to the combined charge of 6.28 E18 electrons).

ampere (A) – the unit of measure for current. One ampere is the movement of one coulomb past

a given point in one second.

current (I) – a flow of electrons (therefore, the flow, or movement, of a charge).

electromotive force (emf) – the force that causes current to flow.

volts (V) – the unit of measure for voltage (and, therefore, emf). An electromotive force of one

volt produces a current flow of one ampere through a resistance of one ohm.


3-22

voltage (E) – another term for electromotive force.

potential difference – a difference in charge between two points. Potential difference is

measured in volts.

resistance (R) – the opposition to current flow in an electric circuit. When current flows through

a resistance of one ohm, there is a potential difference of one volt across the resistor.

ohm – the unit of measure for resistance. 1000 ohms is one kilohm.

EQUIPMENT REQUIRED



Multimeter


3-23

Exercise 1 – Circuit Voltages

EXERCISE OBJECTIVE

Describe and measure voltage in a simple circuit by using a multimeter. Verify results with

information found in this exercise.

EXERCISE DISCUSSION


In this circuit, electron flow occurs because

a. the battery has a neutral charge.

b. unlike charges attract each other.

c. unlike charges repel each other.

EXERCISE PROCEDURE


2. Refer to your SERIES CIRCUIT circuit block. How should you connect your voltmeter to

read the source voltage and indicate its correct polarity?

a. Connect the common side (–) of your meter to the negative terminal of the voltage

source and the positive side (+) to the positive terminal of the voltage source.

b. Connect the common side (–) of your meter to the positive terminal of the voltage source and

the positive side (+) to the negative terminal of the voltage source.

c. Connect both meter terminals to the negative terminal of the voltage source.


3. Connect your voltage meter across the voltage source of your circuit (SERIES CIRCUIT

circuit block). Based on your observation, your meter indicates

a. 0V (with a ± indication).

b. about +15 Vdc.

c. about –15 Vdc.


3-24


4. Reverse the meter connections (black lead to the positive terminal of the voltage source).

Based on your observation, your meter reads

a. 0V.

b. about +15 Vdc.

c. about –15 Vdc.


5. When a voltmeter is connected across a circuit component, reversing the meter leads affects

a. the voltage magnitude and polarity indication.

b. only the polarity indication (voltage magnitude does not change).

c. only the voltage magnitude (polarity indication does not change).

REVIEW QUESTIONS


1. Voltage is

a. potential difference.

b. opposition to current flow.

c. measured with an ammeter.

d. measured with an ohmmeter.


2. Potential difference is measured with a(n)

a. ammeter.

b. ohmmeter.

c. voltmeter.

d. potential meter.


3. An electron represents

a. the basic unit of a charge.

b. a negative charge.

c. a positive charge.

d. a difference in potential.


3-25


4. Electromotive force is

a. a negative charge.

b. a positive charge.

c. zero potential difference.

d. potential difference.


5. A volt is a

a. coulomb in motion.

b. force used to move potential difference.

c. force used to move one coulomb through a resistance of 1Ω.

d. combination of positive and negative charges.

CMS AVAILABLE

None

FAULTS AVAILABLE

None


3-26

Exercise 2 – Circuit Current

EXERCISE OBJECTIVE

Describe and measure current by using a simple circuit. Verify results with a multimeter.

EXERCISE DISCUSSION


In this circuit, voltage and / or resistance change. Circuit current

a. remains constant.

b. is not affected.

c. must change.

EXERCISE PROCEDURE


4. Your ammeter indicates a near zero current because

a. the ammeter opposes the flow of electrons.

b. circuit source voltage is near 0.

c. the circuit resistance opposes the flow of electrons.


5. Adjust the positive supply controls until the ammeter reads 1.0. Does this reading indicate that

circuit current is 1A or 1 mA?

a. 1A because current can be expressed only in amperes.

b. 1 mA because an ammeter set to read milliamps can only indicate 1 mA.

c. 1 mA because the ammeter is set to indicate milliamperes and the circuit current is 1

mA.


7. What is the relationship between the current in your circuit and the applied voltage?

a. Current is directly related to voltage.

b. Current is indirectly related to voltage.

c. Current and voltage are not related.


3-27


8. In your circuit, electrons flow from

a. the negative battery terminal, through the load and meter, and into the positive

battery terminal.

b. both battery terminals and are averaged within the meter.

c. the positive battery terminal, through the load and meter, and into the negative battery

terminal.

REVIEW QUESTIONS


1. An ampere is the unit of measurement for

a. resistance.

b. electron flow.

c. voltage.

d. potential difference.


2. Electron flow moves from what terminal to what terminal of a power source in the external

load?

a. negative, negative

b. negative, positive

c. positive, positive

d. positive, negative


3. Current flowing in a circuit is 0.01 amperes, which is expressed in scientific notation as

a. 10 x 103A.

b. 1 mA.

c. 10 x 10–3A.

d. 10 x 10A.


4. A coulomb is the unit of measurement of

a. an electron.

b. a proton.

c. circuit current.

d. an electrical charge.


3-28


5. A reading of 8.55 mA is expressed in amperes as

a. 0.855A.

b. 0.0855A.

c. 0.00855A.

d. 0.000855A.

CMS AVAILABLE

None

FAULTS AVAILABLE

None


3-29

Exercise 3 – Circuit Resistance

EXERCISE OBJECTIVE

Describe and measure resistance by using a simple circuit. Verify results with a multimeter.

EXERCISE DISCUSSION


In electric circuits, resistance controls the flow of electrons (current flow). An increase in the

conductance of a circuit causes

a. an increase in circuit current.

b. no change in circuit current.

c. a decrease in circuit current.


Based on the EIA color-coding system (click Resources, then click Electronics and

Troubleshooting Help to view the resistor color chart), a 1000Ω, 20% resistor has color bands

of

a. brown, black, and yellow.

b. brown, black, and orange.

c. brown, black, and red.


If the current through a resistor significantly increases, the resistor

a. generates more heat and its physical size should be increased.

b. generates more heat and its physical size should be decreased.

c. size has no effect on power dissipation.


3-30

EXERCISE PROCEDURE


1. Locate the OHM'S LAW circuit block. Based on the EIA color code chart, (click Help) what

are the resistive values of R1and R2?

a. R1 = 51Ω and R2 = 100Ω

b. R1 = 510Ω and R2 = 1000Ω

c. R1 = 5100Ω and R2 = 10,000Ω


2. Use your ohmmeter to verify the values of R1 and R2. Do your measured values agree with

the color code values?

a. Yes. Measured and color-coded values are about the same.

b. No. The values do not agree because the ohmmeter cannot allow for component tolerance.


3. Locate the POWER circuit block. The resistor order with respect to power dissipation

capability (from maximum to minimum) is

a. R4, R1, and R2 or R3.

b. R1, R4, and R2 or R3.

c. R2 or R3, R4, and R1.


5. Monitor your ohmmeter as you vary the R2A control from the extreme CCW position to the

extreme CW position. Based on your observation,

a. the ohmmeter can relate resistance variation to shaft rotation of R2A.

b. resistance is fixed and does not change as the shaft of R2A is rotated.

c. resistance of R2A decreases as the shaft is rotated in a CW direction.


8. Monitor the current of your circuit as you vary the resistance of R2A. Based on your

observation, circuit current increases as

a. the resistance of R2A increases.

b. the resistance of R2A decreases.

c. circuit conductance decreases.


3-31

REVIEW QUESTIONS


1. One characteristic of resistance is that it

a. aids current flow in a circuit.

b. opposes current flow in a circuit.

c. directly related to conductance.

d. directly related to circuit current.


2. What should you use to determine the value of most fixed resistors?

a. the color-coded bands on the resistor

b. the value stamped on the resistor

c. the color code on each schematic

d. the size of the resistor


3. The tolerance of a resistor is determined by the

a. size of the resistor.

b. shape of the resistor.

c. color of the third band.

d. color of the fourth band.


4. A color-coded resistor with bands of yellow, violet, orange, and gold has a 5% tolerance and

an ohmic value of

a. 470Ω.

b. 4.7 kΩ.

c. 47 kΩ.

d. 470 kΩ.


5. The tolerance range of a resistor having a color code of brown, black, red, and gold is from

a. 800Ω to 1200Ω.

b. 900Ω to 1100Ω.

c. 950Ω to 1050Ω.

d. 990Ω to 1010Ω.


3-32

CMS AVAILABLE

None

FAULTS AVAILABLE

None


3-33

UNIT TEST



A term used to describe opposition to current flow is

a. current.

b. power.

c. resistance.

d. voltage.


The opposite of resistance is

a. voltage.

b. current.

c. conductance.

d. coulomb.


Another term for electromotive force is

a. voltage.

b. conductance.

c. resistance.

d. current.


The unit of measurement of electron flow is a(n)

a. volt.

b. ohm.

c. siemen.

d. ampere.


Current flowing in a circuit is 0.015A. This value can also be expressed as

a. 1.5 mA.

b. 15 mA.

c. 150 mA.

d. 10 x 15.


3-34


The ability of a 1/4 watt resistor to give off heat is related to its

a. resistance.

b. tolerance.

c. type of conductance.

d. physical size.


A color-coded resistor with bands of blue, gray, and black has a value of

a. 680Ω at ±1%.

b. 68Ω at ±20%.

c. 6.8Ω at ±5%.

d. 0.68Ω at ±10%.


A precision resistor marked 5 kΩ, ±1% can have a

a. minimum resistance of 495Ω.

b. maximum resistance of 5000Ω.

c. minimum resistance of 4950Ω.

d. maximum resistance of 5010Ω.


The property of conductance is the

a. opposition to current flow.

b. ease of voltage flow.

c. opposition to voltage flow.

d. ease of current flow.


The three important ratings all resistors have are

a. resistance, tolerance, and wattage.

b. size, shape, and wattage.

c. length, diameter, and ability to give off heat.

d. wattage, length, and voltage.

DC Fundamentals Unit 4 – DC Power Sources

3-35

UNIT 4 – DC POWER SOURCES

UNIT OBJECTIVE At the completion of this unit, you will be able to demonstrate battery circuits by using the DC

FUNDAMENTALS circuit board.

UNIT FUNDAMENTALS


In the circuit above, what is the effect of the series connection on individual voltage and current?

a. Only the individual voltages are added.

b. Both voltage and current are added.

c. Only the currents are added.


In the circuit shown, what is the effect of the parallel connection on individual voltage and

current?

a. Only the individual voltages are added.

b. Both voltage and current are added.

c. Only the currents are added.

CMS AVAILABLE

None

FAULTS AVAILABLE

None


3-36

NEW TERMS AND WORDS

storage battery – a cell that can be recharged.

dry cell – a cell containing a moist electrolyte that cannot be spilled. The dry cell can be

operated in any position.

voltaic cells – a device made of three interactive materials that generates electricity.

primary cell – a cell that cannot be recharged.

secondary cells – a cell that can be recharged.

EQUIPMENT REQUIRED



Multimeter


3-37

Exercise 1 – Series and Parallel Battery Circuits

EXERCISE OBJECTIVE

Determine voltage by using batteries connected in series and in parallel. Verify results with a

voltmeter.

EXERCISE DISCUSSION


What is the load (total) voltage of the circuit?

a. 3V

b. 1.5V

c. 0V


What is the total current capability of the parallel battery circuit shown above?

a. 2A

b. 1A

c. 0A


What are the total voltage and total current capabilities of the series/parallel circuit shown

above?

a. 6V and 1A

b. 3V and 2A

c. 3V and 3A


3-38

EXERCISE PROCEDURE


2. Measure the voltage value for V1 of your circuit.

V1 = Vdc

Recall Label for this Question: V1M

Nominal Answer: 1.5

Min/Max Value: (1.35) to (1.65)





Location: Exercise Procedure page: se1p1, Question ID: e1p1c

3. Measure the voltage value for V2 of your circuit.

V2 = Vdc


Nominal Answer: 1.5







4. Based on the measured voltages of your circuit, what is the approximate total voltage of V1

and V2?

V1 = #V1M# Vdc

V2 = #V2M# Vdc

a. 1.5 Vdc

b. 3 Vdc

c. 0 Vdc


5. On your circuit, measure the combined voltage of V1 and V2 (your multimeter should be

placed across both V1 and V2). What does your measurement indicate about the circuit

connection of V1 and V2?

a. V1 and V2 are in parallel.

b. V1 and V2 form a series/parallel connection.

c. V1 and V2 are in series.


3-39


6. Measure the voltage across V3 without the two-post connector in place.

V3 = Vdc


Nominal Answer: 1.5

Min/Max Value: (1.305) to (1.695)






7. Measure the voltage across V4 without the V3 two-post connector in place.

V4 = Vdc


Nominal Answer: 1.5

Min/Max Value: (1.305) to (1.695)






8. Use a two-post connector to connect V3 and V4. Measure the voltage across V3 and V4.

which statement is correct?

a. V3 and V4 are in series and the total voltage equals the voltage of either cell.

b. V3 and V4 form a series / parallel combination.

c. V3 and V4 are in parallel and the total voltage equals the voltage of either cell.


9. Depress and release S1, then S2, and observe the circuit LED. Why does S1 cause the LED to

be brighter?

a. S1 is connected to a parallel battery circuit. The voltage of each cell is added to provide more

energy for the LED.

b. S1 is connected to a series battery circuit. The voltage of each cell is added to provide

more energy for the LED.

c. S2 is connected to a parallel battery circuit. The voltage of each cell is added to provide less

energy for the LED.


3-40

REVIEW QUESTIONS


1. Cells are connected in series to

a. increase the voltage output.

b. decrease the voltage output.

c. increase the current capability.

d. decrease the current capability.


2. If each 1.5V cell in the circuit shown has a current capability of 0.5A, the total circuit

voltage and current capability when S1 is closed is

a. 1.5V and 0.5A.

b. 1.5V and 1A.

c. 3V and 0.5A.

d. 3V and 1A.


3. If each 1.5V cell in the circuit shown has a current capability of 0.5A, the total circuit

voltage and current with switch S2 closed is

a. 1.5V and 0.5A.

b. 1.5V and 1A.

c. 3V and 0.5A.

d. 3V and 1A.


4. Cells are connected in parallel to



c. increase the current capability.

d. decrease the current capability.


5. A cell in a lead-acid battery, which is made of wet cells, has a voltage of

a. 1.25V.

b. 1.4V to 1.6V.

c. 1.5V to 2V.

d. 2V to 2.2V.


3-41

CMS AVAILABLE

None

FAULTS AVAILABLE

None


3-42

Exercise 2 – Series-Opposing DC Sources

EXERCISE OBJECTIVE

Determine voltage by using series-opposing power connections. Verify results with a voltmeter.

EXERCISE DISCUSSION


In the circuit above, two cells are series-aiding and are then connected as series-opposing to a

third cell. What is the total voltage of the circuit?

a. 3V

b. 1.5V

c. 0.5V

EXERCISE PROCEDURE


V5 = Vdc


Nominal Answer: 5.6

Min/Max Value: (4.872) to (6.328)






4. Measure the difference of potential between the positive terminals of V5 and V6. The meter

indicates near 0V because the

a. variable supply is connected to the RED meter lead.

b. circuit batteries are series-aiding.

c. circuit batteries are series-opposing.


3-43


V6 = Vdc


Nominal Answer: 1.6







7. Based on a total circuit voltage of -4 Vdc, which statement below is correct?

V5 = #V5M# Vdc

V6 = #V6M# Vdc

a. The total voltage given is correct because the batteries are series-aiding.

b. The total voltage given is correct because the batteries are series-opposing.

c. Meter polarity is not given; therefore, you cannot determine total voltage.


8. To determine total circuit voltage, the voltage values of V5 and V6 must be subtracted from

each other. Why?

a. V5 and V6 are series- opposing.

b. V6 is variable and its voltage value is added to that of V5.

c. V6 opposes the combined V5 and meter- generated voltages.


9. Activate the circuit LEDs with a two-post connector. Adjust V6 until both LEDs are off. Why

are the circuit LEDs off while V5 and V6 apply power to the circuit?

a. V5 and V6 are about the same value and are series-opposing.

b. V5 and V6 are series-opposing and place 11.2 Vdc across the LEDs.

c. V5 and V6 are series-aiding and place 11.2 Vdc across the LEDs.


10. Adjust V6 (the positive variable supply) controls to the maximum clockwise position. Why is

the YELLOW LED on?

a. V6 is higher in value than V5, generating a positive differential voltage.

b. V6 is lower in value than V5, generating a negative differential voltage.

c. V6 and V5 are now series-aiding.


3-44


11. Adjust V6 (the positive variable supply) controls to the maximum counterclockwise position.

Why is the GREEN LED on?

a. V6 is higher in value than V5, generating a positive differential voltage.

b. V6 is lower in value than V5, generating a negative differential voltage.

c. V6 and V5 are now series-aiding.

REVIEW QUESTIONS


1. A series-opposing circuit is made up of two batteries connected

a. positive to negative.

b. negative to positive.

c. negative to negative and positive to positive.

d. either negative to negative or positive to positive.


2. In a series-opposing circuit, the total voltage equals the

a. difference between individual battery voltages.

b. sum of the individual battery voltages.

c. way the batteries are connected.

d. types of batteries used.


3. Two voltage sources of equal value are series-opposing. What is the output voltage?

a. two-thirds

b. double

c. one-half

d. zero


4. Three 1.5V dry cells are connected as shown. How much voltage is available at the output

terminals?

a. 0 Vdc

b. 1.5 Vdc

c. 3.0 Vdc

d. 4.5 Vdc


3-45


5. If the overall circuit potential difference in the circuit shown is +5.20 Vdc, the value of

battery V6 is

a. +0.4 Vdc.

b. +5.6 Vdc.

c. +10.8 Vdc.

d. +12 Vdc.

CMS AVAILABLE

None

FAULTS AVAILABLE

None


3-46

UNIT TEST



The output of a lead-acid cell is approximately

a. 1.25V.

b. 1.45V.

c. 2.1V.

d. 4V.


Cells are connected in series aiding to



c. increase the current capacity.

d. decrease the current capacity.


Cells are connected in parallel to



c. increase the current capacity.

d. decrease the current capacity.


Which of the following cells is a dry secondary cell?

a. carbon-zinc

b. silver-oxide

c. lead-acid

d. nickel-cadmium


The total voltage and current capabilities of the circuit shown

above are

a. 1.5V and 0.5A.

b. 4.5V and 0.5A.

c. 4.5V and 1.5A.

d. 1.5V and 1.5A.


3-47


A series-opposing circuit is made up of two batteries connected

a. positive to negative.

b. negative to positive.

c. negative to negative and positive to positive.

d. either positive to positive or negative to negative.


The total voltage in the circuit shown is

a. 1.5V.

b. 3V.

c. 4.5V.

d. 7.5V.


The total current capability of the circuit shown is

a. 2.5A.

b. 1.5A.

c. 0.5A.

d. 1A.


The potential difference in the circuit shown is

a. 2.5V.

b. 3V.

c. 5.5V.

d. 8.5V.


In a series-opposing circuit, the total voltage equals the

a. sum of each cell.

b. difference between each cell.

c. way the cells are connected.

d. types of cells used in the circuit.


3-48

DC Fundamentals Unit 5 – Switches and Switching Concepts

3-49

UNIT 5 – SWITCHES AND SWITCHING CONCEPTS

UNIT OBJECTIVE Identify types of switches and demonstrate switch circuit operation by using a multimeter and

LEDs.

UNIT FUNDAMENTALS


In a circuit, the switch is in its ON position. What is the contact resistance of the switch?

a. high

b. some intermediate value

c. low

CMS AVAILABLE

None

FAULTS AVAILABLE

None

NEW TERMS AND WORDS

pole – the current-carrying moveable part or parts of a switch that closes and opens an electrical

circuit.

contacts – the current-carrying part of a switch that closes and opens an electrical circuit.

SPST – abbreviation for Single Pole Single Throw switch; switch with two terminals used to

connect one terminal to the other terminal.

DPST – abbreviation for Double Pole Single Throw switch; a switch with four terminals used to

connect one pair of terminals to the other pair of terminals.

SPDT – abbreviation for Single Pole Double Throw switch; switch with three terminals used to

connect one terminal to either of the other two terminals.

DPDT – abbreviation for Double Pole Double Throw switch; a switch with six terminals used to

connect one pair of terminals to either of the other two pairs.

PBNO – abbreviation for PushButton Normally Open; switch whose terminals are connected

when its pushbutton is depressed.

PBNC – abbreviation for PushButton Normally Closed; switch whose terminals are connected

when its pushbutton is not depressed.


3-50

EQUIPMENT REQUIRED

F.A.C.E.T base unit


Multimeter


3-51

Exercise 1 – Identify Types of Switches

EXERCISE OBJECTIVE

Identify switch functions by using a multimeter. Verify results with information found in this

exercise.

EXERCISE DISCUSSION


In the figures, A and B represent which types of switches, respectively?

a. SPST and DPST with shorted poles

b. SPST and DPST

c. SPST and SPDT with independent poles

Location: Exercise Discussion page: se1d6, Question ID: e1d6

In the figure, the switch determines which lamp is energized. Which type of switch is

represented?

a. SPST

b. DPST

c. DPDT


S1 and S2 represent which types of switches, respectively?

a. normally closed and normally open pushbuttons

b. slide switch with isolated poles

c. double-pole toggle switch


3-52

EXERCISE PROCEDURE


3. Select the ohms function on your multimeter. Measure the resistance between each set of

contacts (upper and lower) of S3. Based on your measurement, which of the following is correct?

a. One set of contacts is closed while the other is open. The closed side indicates 0Ω. The

open side indicates infinity.

b. Both sets of contacts are open and indicate infinity.

c. Both sets of contacts are closed and indicate 0Ω.


Based on your measurements, which of the following is correct?

a. The upper contacts are open and the lower contacts are closed.

b. The open contacts indicate infinity and the closed contacts indicate 0Ω.

c. All of the above.


5. On the SWITCHES circuit block, locate S1 and S2. Based on the silkscreened switch symbols,

which of the following statements is correct?

a. S1 and S2 are PBNO switches.

b. S1 is a PBNC switch and S2 is a PBNO switch.

c. S1 and S2 are PBNC switches.


6. Use your ohmmeter to measure the switch resistance of S1. Repeat the measurement when you

depress the switch button. Based on the meter indication, which statement is correct?

a. The initial resistance of S1 is 0Ω. Its resistance is infinity when the S1 pushbutton is

activated (pressed down).

b. The initial resistance of S1 is 0Ω. Its resistance does not change when the S1 pushbutton is

activated.

c. The initial resistance of S1 is infinity. Its resistance is 0Ω when the S1 pushbutton is

activated.


3-53


7. Use your ohmmeter to measure the switch resistance of S2. Repeat the measurement when you

depress the switch button. Based on the meter indication, which statement is correct?

a. The initial resistance of S2 is 0Ω. Its resistance is infinity when the S2 pushbutton is

activated.

b. The initial resistance of S2 is infinity. Its resistance does not change when the S2 pushbutton

is activated.

c. The initial resistance of S2 is infinity. Its resistance is 0Ω when the S2 pushbutton is

activated.


8. Locate S4 in the SWITCHES circuit block. What type of switch is S4?

a. DPDT toggle switch

b. DPDT pushbutton switch

c. DPDT slide switch


9. Place slide switch S4 in the UP position (toward the ZIF connector). Use your ohmmeter to

measure the resistance of each contact pair. Based on your measurements, which statement is

correct?

a. The lower set of contacts of each pole are made. No electrical connection is indicated

between the poles of S4.

b. The upper set of contacts of each pole are made. No electrical connection is indicated

between the poles of S4.

c. The upper set of contacts of each pole are made. Both switch poles are electrically connected

and all four made contacts are shorted together.


3-54

REVIEW QUESTIONS


1. In electrical circuits, switches

a. control current flow.

b. open circuits.

c. close circuits.



2. The switch that controls one conductor with two loads is a(n)

a. SPST switch.

b. SPDT switch.

c. rotary switch.

d. DIP switch.


3. In this circuit, a switch that opens a circuit when pressed is

a. S1.

b. S2.

c. S3.

d. S4.


4. In this circuit, the DPDT switch controls

a. one conductor in one circuit.

b. one conductor in two circuits.

c. two conductors in two circuits.

d. two conductors in one circuit.


5. In this circuit, a switch classified as PBNO is

a. S1.

b. S2.

c. S3.

d. S4.


3-55

CMS AVAILABLE

None

FAULTS AVAILABLE

None


3-56

Exercise 2 – Switching Concepts

EXERCISE OBJECTIVE

Demonstrate basic switch-controlled circuits by using the trainer. Use LEDs and a multimeter to

verify results.

EXERCISE DISCUSSION

No Questions

EXERCISE PROCEDURE


2. What type of switch is S1 and why is the RED LED on?

a. S1 is a normally open switch. An open switch allows current to flow through the RED LED,

turning it on.

b. S1 is a normally closed switch. A closed switch allows current to flow through the RED

LED, turning it on.

c. S1 is a shorted switch. The RED LED will always be on because the switch is shorted by its

pole.


3. Press and hold pushbutton switch S1. Why is the RED LED off when you activate S1?

a. Because activating S1 closed, or made, the switch contacts.

b. Because current flows through the normally closed switch S1.

c. Because activating S1 opens its normally closed contacts and current no longer flows

through the LED.


5. Press and release S2. Based on the indication of the GREEN LED, which statement is correct?

a. S2 is normally closed. Activating S2 breaks the circuit, causes current to flow, and turns on

the GREEN LED.

b. S2 is normally open. Activating S2 makes the circuit, causes current to flow, and turns

on the GREEN LED.

c. S2 is normally open. Activating S2 breaks the circuit, causes current to flow, and turns on the

GREEN LED.


3-57


8. Move the handle of S3 up and down several times. Note the action of each LED in relation to

the position of S3. Based on your observation, which statement is correct?

a. An SPDT switch makes two loads simultaneously, as indicated by the RED and GREEN

LEDs.

b. The RED and GREEN LEDs indicate current flow in one circuit at a time.

c. An SPDT switch breaks two loads simultaneously, as indicated by the RED and GREEN

LEDs.


10. Slide the handle of S4 up and down, and observe the operation of both circuit LEDs. Based

on your observation, which statement is correct?

a. Both poles of S4 make and break a circuit simultaneously.

b. It is possible to adjust the switch poles so that both LEDs are off.



11. Based on a comparison between your ohmmeter indications, the RED and GREEN LEDs,

and the position of S4, which statement is correct?

a. With S4 in the UP position, both upper poles make and both lower poles break.

b. With S4 in the UP position, both upper poles break and both lower poles make.

c. With S4 in the DOWN position, an upper pole makes on one side and a lower pole makes on

the other side.


12. Based on your observations, can each switch pole of the DPDTswitch (S4) perform the

function of the SPDT switch (S3)?

a. no

b. yes

c. yes, provided that both poles of the double-pole switch are used together


3-58

REVIEW QUESTIONS


1. In this circuit, the GREEN LED is on when

a. S1 is pressed.

b. S4 is in the UP position as shown.

c. S3 is in the UP position.

d. S2 is pressed.


2. An SPDT switch can connect

a. one conductor to either of two loads.

b. two conductors to three single conductors.

c. one conductor to one single load only.

d. two conductors to either of two conductors.


3. A PBNC switch is

a. open when not pressed.

b. closed when not pressed.

c. used to control two conductors.

d. made up of two poles.


4. A single-pole single-throw switch connects

a. one conductor to two conductors.

b. two conductors to two loads.

c. one conductor to one conductor.

d. two conductors to one load.


5. A double-pole switch consists of

a. two mechanically independent SPDT switches.

b. one electrically independent single pole switch.

c. two electrically independent single pole switches.

d. one mechanically independent SPDT switch.


3-59

CMS AVAILABLE

None

FAULTS AVAILABLE

None


3-60

UNIT TEST



Which statement best describes the pole of a switch?

a. A pole is the movable part of a switch.

b. A pole is the fixed contact of a switch.

c. A pole is used in very few switches.

d. A pole cannot carry current.


Which type of switch can control only one circuit?

a. SPST

b. SPDT

c. DPST

d. DPDT


A pushbutton switch can be identified as a(n)

a. PBNC switch.

b. PBNO switch.

c. SPST switch.



A DPDT switch must be used to connect

a. one conductor to one circuit.

b. two conductors to two circuits.

c. one conductor to two circuits.

d. two conductors to one circuit.


In this circuit, which switch is classified as PBNO?

a. S1

b. S2

c. S3

d. S4


3-61


When a switch is closed, its contacts have a

a. maximum voltage drop and minimum resistance.

b. minimum voltage drop and maximum resistance.

c. minimum voltage drop and minimum resistance.

d. maximum voltage drop only.


Maximum current flows in a circuit when a(n)

a. switch is open.

b. SPST switch is used.

c. DPST switch is used.

d. switch is closed.


If all circuits shown are energized, the RED LED will be on when

a. S4 is in the DOWN position.

b. S2 is not pressed.

c. S3 is in the DOWN position.

d. S1 is not pressed.


If all circuits shown are energized, the GREEN LED will be on when

a. S1 is not pressed.

b. S2 is not pressed.

c. S3 is in the DOWN position.

d. S4 is in the UP position.


What single switch can be used to duplicate the action of two SPDT switches?

a. DPDT

b. DPST

c. PBNC

d. SPST


3-62

DC Fundamentals Unit 6 – Ohm's Law

3-63

UNIT 6 – OHM'S LAW

UNIT OBJECTIVE

Demonstrate the relationship of resistance, current, and voltage by using Ohm's law.

UNIT FUNDAMENTALS


Ohm's law deals with the relationship of voltage, current, and resistance. Which statement

defines the relationship?

a. Voltage provides the pressure needed to overcome resistance and produce a flow of

current.

b. Resistance provides the pressure needed to overcome voltage and produce a flow of current.

c. Current provides the pressure needed to produce a flow of voltage through a resistance.


A resistor has a color code starting with a band of brown, followed with bands of black, red, and

gold. What are its nominal resistance value and tolerance (in percent)?

a. 10,000Ω and ±5%

b. 1000Ω and ±10%

c. 1000Ω and ±5%

CMS AVAILABLE

None

FAULTS AVAILABLE

None

NEW TERMS AND WORDS

ohm's law – In any dc electric circuit, the current is directly proportional to the voltage and

inversely proportional to the resistance. In its simplest form, Ohm's law is expressed

mathematically as E = IR (voltage equals current times resistance).

EQUIPMENT REQUIRED



Multimeter


3-64

Exercise 1 – Ohm's Law - Circuit Resistance

EXERCISE OBJECTIVE

Determine resistance by using Ohm's law. Verify results with a multimeter.

EXERCISE DISCUSSION


In a circuit with an applied voltage of 10V, circuit current measures 15 mA (0.015A). What is

the value of circuit resistance?

a. Circuit resistance equals 6670Ω.

b. Circuit resistance equals 667Ω.

c. Circuit resistance cannot be determined.

EXERCISE PROCEDURE


R1 = Ω

Recall Label for this Question:


Min/Max Value: (510) to (510)






R2 = Ω









3-65


3. Using the ohms function of your multimeter, measure and enter the value of R1. Your

measured value for R1 and its nominal color code value should be approximately equal.

R1 = Ω

Recall Label for this Question: R1M








4. Using the ohms function of your multimeter, measure and enter the value of R2. Your

measured value for R2 and its nominal color code value should be approximately equal.

R2 = Ω








Location: Exercise Procedure page: se1p2, Question ID: e1p2e

5. Insert a two-post connector between R1 and R2. Using the ohms function of your

multimeter, measure and enter the value of the total circuit resistance (RT).

RT = Ω

Recall Label for this Question: RTM



Value Calculation: 1500





3-66


6. Set your multimeter to read voltage. Adjust the positive variable supply for 10 Vdc. Enter

your voltage reading in volts.

VA = Vdc

Recall Label for this Question: VA








8. Enter your total circuit current (IT) in milliamps (0.001A = 1 mA).

IT = mA

Recall Label for this Question: IT

Nominal Answer: 6.6







RT = Ω

Recall Label for this Question: RTC

Nominal Answer: 1515.0 *Min/Max Value: ( 1074) to ( 2341)

Value Calculation: ( #VA# / #IT# ) * 1000




* NOTE: Min/Max Values shown are based upon a calculation using the absolute

lowest and highest recall value. By using the actual input in your calculations, you

will determine the correct value.


3-67


10. Compare the measured total resistance (#RTM#Ω) with your calculated total resistance

(#RTC#Ω). Based on your results, which statement is correct?

a. Applying voltage and current to Ohm's law does not provide an accurate total circuit

resistance.

b. Ohm's law, in the form of voltage/current, provides an accurate total resistance value.

c. Ohm's law will not apply to total circuit resistance unless the applied voltage and circuit

current are equal in value.


11. CM 19 is activated. Use your multimeter to measure the total current (IT) of your circuit.

Ensure that the applied voltage is set for 10 Vdc.

IT = mA

Recall Label for this Question: ITCM19


Min/Max Value: (1.883) to (3.497)






Total circuit resistance = Ω

Recall Label for this Question: RTCCM19


Value Calculation: 10 / #ITCM19# * 1000








3-68


13. Remove power from your circuit by removing the ammeter between the voltage source and

the top of R1. Measure the total circuit resistance (CM 19 is activated). Does your measured

value approximately equal the calculated total resistance of #RTCCM19#Ω?

a. No. The values do not agree because the individual component resistances are not known.

b. Yes. The values are about the same because the added resistor increased the circuit's total

current.

c. Yes. Although the circuit was modified, Ohm's law (E/I = R) holds true.


R2 = Ω

Recall Label for this Question: RECM19








15. Based on the information given in the circuit, how can you determine the value of R1?

a. Divide the voltage drop of R1 by the circuit current.

b. Divide the voltage drop of R2 by the circuit current.

c. Divide the applied voltage (VA) by the circuit current.


3-69

REVIEW QUESTIONS


1. Resistance and current are

a. measured in the same units.

b. inversely proportional.

c. directly proportional.

d. always smaller than the voltage.


2. If the resistance in a circuit is doubled and the voltage remains the same, the current

a. remains the same.

b. is doubled.

c. is halved.

d. may increase or decrease.


3. In an electric circuit, if the current is 20 mA and the voltage is 40V, the circuit resistance is

a. 20Ω.

b. 200Ω.

c. 2000Ω.

d. 20000Ω.


4. On the OHM'S LAW circuit block, CM 19 is activated. With your ohmmeter, determine

which resistor (R1 or R2) changed and its new value.

a. R2, 250Ω

b. R2, 510Ω

c. R1, 1000Ω

d. R2, 3200Ω


5. When you use Ohm's law, how many values must be known?

a. one

b. two

c. three

d. all values


3-70

CMS AVAILABLE

CM 19

FAULTS AVAILABLE

None


3-71

Exercise 2 – Ohm's Law - Circuit Current

EXERCISE OBJECTIVE

Determine current by using Ohm's law. Verify with a multimeter.

EXERCISE DISCUSSION


In this circuit, the voltage is increased and the resistance is decreased. Based on Ohm's law, what

is the effect on circuit current?

a. The circuit current must increase.

b. There is no change in circuit current.

c. The circuit current must decrease.

EXERCISE PROCEDURE


2. Measure the total resistance of your circuit and enter your value in ohms.

RT = Ω

Recall Label for this Question: RTMM








3-72


5. Calculate the expected circuit current based on an applied voltage of 10 Vdc and a circuit

resistance of #RTMM#Ω. Enter your result in milliamps (0.001A = 1 mA).

IT = mA

Recall Label for this Question: ITC


Min/Max Value: (4.84 ) to (9.934)

Value Calculation: 10/#RTMM#*1000





8. Enter the current reading of your circuit in milliamps.

IT = mA

Recall Label for this Question: ITM


Min/Max Value: (4.669) to (8.671)






9. The calculated circuit current equals #ITC# mA and the measured circuit current equals

#ITM# mA. Based on a comparison of the two values, is a calculation based on Ohm's law a true

indication of circuit current?

a. No. Ohm's law cannot be considered accurate.

b. Yes. Ohm's law provides a true indication of circuit current.

c. Yes. Ohm's law provides a true indication of circuit current but only when circuit resistances

and voltages are measured.


3-73


IT = mA

Recall Label for this Question: ITCN

Nominal Answer: 3.311 *Min/Max Value: (2.42 ) to (4.967)

Value Calculation: 5 / #RTMM# * 1000





11. Ensure that you change the applied voltage to 5 Vdc. Measure the current of your circuit.

Compare your meter indication to the calculated current of #ITCN# mA. Does Ohm's law hold

true when the circuit's applied voltage is changed?

a. No.

b. Yes, provided the calculation uses the original circuit voltage.

c. Yes, provided the calculation uses the new circuit voltage.


RT = Ω

Recall Label for this Question: RTMCM20


Min/Max Value: (871.5) to ( 1619)









3-74


13. Adjust the positive variable supply for 10 Vdc. Based on a circuit resistance of

#RTMCM20#Ω and a circuit voltage of 10 Vdc, measure and enter the circuit current (in

milliamps).

IT = mA

Recall Label for this Question: ITMCM20


Value Calculation: 10 / #RTMCM20# * 1000





14. Based on the given tabulated results, which statement represents the relationship between

current, voltage, and resistance?

a. Current, voltage, and resistance are directly related.

b. Current, voltage, and resistance are inversely related.

c. Current is directly related to voltage but inversely related to resistance.

REVIEW QUESTIONS


1. Voltage and current are

a. measured in the same unit.



d. always larger than the resistance.


2. If the voltage in a circuit is doubled and the resistance remains the same, the current


b. is doubled.

c. is halved.

d. may increase or decrease.





3-75


3. In an electric circuit, if the voltage is 20 Vdc and the resistance is 4000Ω, the circuit current

is

a. 5 mA.

b. 0.005A.


d. None of the above.


4. In an electrical circuit having a voltage of 8 Vdc and a resistance of 1.5 kΩ, the circuit

current is

a. 5.3 mA.

b. 9.5 mA.

c. 12 mA.

d. 18.75 mA.


5. CM 19 is activated. Refer to the OHM'S LAW circuit block. Adjust the positive supply to 7

Vdc. Determine the value of total circuit resistance and circuit current.

a. 510Ω, 13.7 mA

b. 1245Ω, 5.6 mA

c. 1510Ω, 4.6 mA

d. 3710Ω, 1.88 mA

CMS AVAILABLE

CM 20

CM 19

FAULTS AVAILABLE

None


3-76

Exercise 3 – Ohm's Law - Circuit Voltage

EXERCISE OBJECTIVE

Determine voltage by using Ohm's law. Verify results with a multimeter.

EXERCISE DISCUSSION


In this circuit, circuit resistance is doubled and circuit current decreases by half. What is the new

applied voltage?

a. 20 Vdc

b. 10 Vdc

c. 5 Vdc

EXERCISE PROCEDURE


3. Adjust the positive supply for a current reading of approximately 3.68 mA. Enter your

reading.

IT = mA

Recall Label for this Question: ITSET


Min/Max Value: (3.496) to (3.864)






3-77


4. Based on your circuit current of #ITSET# mA and a nominal circuit resistance of 1510Ω,

calculate and enter the expected applied voltage.

VA= Vdc

Recall Label for this Question: EC


Value Calculation: 1510 / 1000 * #ITSET#





5. Measure the applied voltage of your circuit. Compare your reading to the calculated value of

#EC#V. Do your results indicate that Ohm's law can be used to determine circuit voltage when

current and resistance are known?

a. No, applied voltage must be measured.

b. Yes.

c. Yes, but only if voltage is adjusted for a specific current.


6. Based on a circuit current of #ITSET# mA, use Ohm's law (I x R) to calculate the voltage

drop of R1 of your circuit.

VR1 = Vdc

Recall Label for this Question: VR1C


Value Calculation: #ITSET# *510 / 1000








3-78


7. Based on a circuit current of #ITSET# mA, use Ohm's law (I x R) to calculate the voltage

drop of R2.

VR2 = Vdc

Recall Label for this Question: VR2C


Value Calculation: #ITSET#





8. Energize your circuit with a two-post connector. Measure the voltage drop of R1.

VR1 = Vdc

Recall Label for this Question: VR1M


Min/Max Value: (1.316) to (2.444)






9. Measure the voltage drop of R2.

VR2 = Vdc



Min/Max Value: (2.576) to (4.784)









3-79


10. Based on the data you generated, which statement applies with respect to Ohm's law?

a. Ohm's law cannot be used to determine individual resistive voltage drops.

b. Ohm's law can be used only to determine the circuit applied voltage.

c. Ohm's law can be used to determine both applied voltage and individual resistive

voltage drops.


12. CM 19 is activated. Measure and enter the circuit current in milliamps.

IT = mA

Recall Label for this Question: ITCMM19

Nominal Answer: 2.7







13. What new circuit applied voltage is required to reduce the current from #ITCMM19# mA to

1.35 mA?

a. Applied voltage cannot be changed unless circuit resistance is changed.

b. 15 Vdc

c. 5 Vdc


14. Adjust the positive supply to 5 Vdc. Measure the circuit current (CM 19 is activated) and

compare your reading to #ITCMM19# mA. Does a 50% reduction in applied voltage reduce the

current by a like amount?

a. Yes. If the resistance is held constant, a 50% applied voltage reduction decreases the

circuit current by a like amount.

b. Yes, provided that the circuit resistance is decreased by a like amount.

c. Yes, provided that the circuit resistance is increased by a like amount.


15. Based on your observations, which statement about voltage, current, and resistance is

correct?

a. If voltage increases, current decreases when resistance is held constant.

b. If voltage increases, current increases when resistance is held constant.

c. If voltage increases, both current and resistance must decrease.


3-80

REVIEW QUESTIONS


1. Voltage and resistance are

a. measured in the same unit.



d. smaller than circuit current.


2. An electric circuit with 500Ω of resistance and 20 mA of current flow requires an applied

voltage of

a. 5 Vdc.

b. 10 Vdc.

c. 15 Vdc.

d. 50 Vdc.


3. If the voltage and resistance in a circuit are both doubled, the current will

a. increase.

b. decrease.

c. double.

d. remain the same.


CM 20 is activated. Based on the change of circuit current, voltage drops, and Ohm's law, which

component in the circuit block changed?

a. R1 increased in value.

b. R2 increased in value.

c. R1 decreased in value.

d. R2 decreased in value.


5. In this circuit, suppose you measured a circuit current of 5 mA. The reason for the increased

current could be that

a. R1 changed to 2500Ω.

b. R2 changed to 1000Ω.

c. R1 changed to 1500Ω.

d. R2 changed to 400Ω.


3-81

CMS AVAILABLE

CM 19

CM 20

FAULTS AVAILABLE

None


3-82

UNIT TEST



In any dc electrical circuit, voltage and current are

a. always larger than the resistance.

b. measured in the same units.

c. inversely proportional.

d. directly proportional.


In an electric circuit where the voltage and resistance are known, which form of Ohm's law is

used to find the circuit current?

a. I = I x R

b. I = R/E

c. I = E/R

d. I = E x R


When you use any form of Ohm's law, how many values must be known?

a. one

b. two

c. three

d. none


If the voltage applied to a circuit is halved while the resistance remains the same, the current


b. is halved.

c. is doubled.

d. increases.


If an electric circuit has a current of 15.4 mA and a source voltage of 20 Vdc, the total resistance

is

a. 1300Ω.

b. 1500Ω.

c. 1800Ω.

d. 2000Ω.


3-83


A milliampere is

a. one thousand times larger than an ampere.

b. equal to 10 x 103.

c. one thousand times smaller than an ampere.

d. equal to 10 x 10–3.


Resistance and current are

a. measured in the same units.



d. always smaller than voltage.


Ohm's law is used to solve for circuit

a. current.

b. resistance.

c. voltage.



In an electric circuit, if the current is 2.5 mA and the resistance is 3 kΩ, the source voltage is

a. 2.5V.

b. 4.5V.

c. 5.5V.

d. 7.5V.


In an electric circuit where the voltage is 100V and the resistance is 25 kΩ (25,000Ω), the

current is

a. 4 mA.

b. 25 mA.

c. 25A.

d. 40A.


3-84

TROUBLESHOOTING

Location: Troubleshooting page: ttrba2, Question ID: trba2a

3. To check the performance of your circuit, measure the voltage drop of R1 (the nominal value

equals 3.38 Vdc). Enter the value of VR1 below.

VR1 = Vdc



Min/Max Value: (3.033) to (3.707)





Location: Troubleshooting page: ttrba3, Question ID: trba3

5. The faulty component in the OHM'S LAW circuit block is

a. R1, which is open.

b. R1, which is shorted.

c. R2, which is open.

d. R2, which is shorted.

CMS AVAILABLE

None

FAULTS AVAILABLE

Fault 12

DC Fundamentals Unit 7 – Series Resistive Circuits

3-85

UNIT 7 – SERIES RESISTIVE CIRCUITS

UNIT OBJECTIVE

Determine the values of resistance, current, and voltage in a series resistive circuit by using

Ohm's law.

UNIT FUNDAMENTALS


In a series circuit, does current flow require an open or closed circuit path?

a. open

b. closed

c. either open or closed, provided the resistors are connected one after the other.


In this circuit, what is the value of the applied circuit voltage?

a. 5 Vdc

b. 10 Vdc

c. 15 Vdc


With respect to the reference point (REF), how are points A and D related?

a. A is positive and D is negative.

b. A is negative and D is positive.

c. A and D have the same polarity because REF is between the resistors.

CMS AVAILABLE

None

FAULTS AVAILABLE

None


3-86

NEW TERMS AND WORDS

voltage drop – the amount of voltage across any resistor in a circuit; also called IR drop.

series string – a combination of two or more resistances in series.

EQUIPMENT REQUIRED



Multimeter


3-87

Exercise 1 – Resistance in a Series Resistive Circuit

EXERCISE OBJECTIVE

Determine the total resistance of series resistive circuits by using a formula. Verify results with a

multimeter.

EXERCISE DISCUSSION

No Questions

EXERCISE PROCEDURE


1. Locate the SERIES CIRCUIT circuit block. Based on the resistor color code, what are the

resistive values of R1, R2, and R3?

a. R1 = 100Ω, R2 = 120Ω, R3 = 62Ω

b. R1 = 1000Ω, R2 = 1200Ω, R3 = 620Ω

c. R1 = 10 kΩ, R2 = 1.2 kΩ, R3 = 6.2 kΩ


2. What is the total resistance of the string making up the SERIES CIRCUIT circuit block?

a. RT = 282Ω

b. RT = 2820Ω

c. RT = 28,200Ω


3. Measure and enter the total resistance of your circuit.

RT = Ω









3-88


4. Based on your observations, how can you determine the total resistance of a series string?

a. Apply power to the string, and measure or calculate the total resistance.

b. Add the resistive values of each component in the string, or measure the total resistance

of the string.

c. Add the resistances of each component within the string, and subtract the total value from the

measured value.


5. CM 1 is activated. Measure the resistance of R1.

R1 = Ω

Recall Label for this Question: R1CM1








6. CM 1 is still activated. Measure the resistance of R2.

R2 = Ω









7. CM 1 is still activated. Measure the resistance of R3.

R3 = Ω









3-89


8. Use your measured values to calculate the total resistance with CM 1 activated.

RT = Ω

Recall Label for this Question: RTCM1


Value Calculation: # R1CM1 + R2CM1 + R3CM1 #





9. Did CM 1 increase or decrease the total string resistance? Why?

a. Decrease. The value of R1 decreased.

b. Increase. The value of R1 increased.

c. Increase. The value of R1 decreased.


10. CM 1 is deactivated. Based on your observations, what is the relationship between a series

string and the resistors that make up the string?

a. The total string resistance decreases if the sum of the individual resistances decreases.

b. The total string resistance increases if the sum of the individual resistances increases.






3-90

REVIEW QUESTIONS


1. The total resistance of three series-connected resistors with color bands of yellow, violet, red,

gold; red, red, red, gold; and orange, orange, brown, gold is

a. 7230Ω.

b. 10,200Ω.

c. 47,300Ω.

d. 72,300Ω.


2. How many current paths can a series circuit have?

a. 4

b. 3

c. 2

d. 1


3. In a series circuit, the total resistance

a. is less than the resistance of any individual resistor.

b. is inversely proportional to the amount of source voltage.

c. equals the sum of the individual resistances.

d. increases when the circuit current increases.


4. To measure the value of a resistor, connect the ohmmeter

a. across the resistor with power on.

b. across the resistor with power off.

c. in series with the resistor with power on.

d. in series with the resistor with power off.


5. The total resistance of three series-connected resistors with resistances of 1.5 kΩ, 6.8 kΩ,

and 4.7 kΩ is

a. 13,000Ω.

b. 130 kΩ.

c. 130,000Ω.

d. 133 kΩ.


3-91

CMS AVAILABLE

CM 1

FAULTS AVAILABLE

None


3-92

Exercise 2 – Current in a Series Resistive Circuit

EXERCISE OBJECTIVE

Determine the current flow in a series resistive circuit by using a formula. Verify results with a

multimeter.

EXERCISE DISCUSSION


In a series string, what is the relationship between circuit current and the distribution of that

current through each resistor of the string?

a. The current through each resistor is the same and equal to the circuit current.

b. The current through each resistor varies in direct proportion to the value of the resistor.

c. The current through each resistor varies in inverse proportion to the value of the resistor.


In a series circuit, the same current flows through each resistor. Current flow through a resistor

generates a voltage drop. How can the voltage drop of a resistor be used to determine total circuit

current?

a. Individual voltage drops cannot be used to determine total circuit current.

b. Use IT = VR x R.

c. Use IT = VR /R.


3-93

EXERCISE PROCEDURE


2. Measure the value of the voltage source.

VA = Vdc

Recall Label for this Question: VAM


Min/Max Value: (14.55) to (15.45)






3. Calculate the total resistance of your circuit. Use the nominal color code values for each

resistor.

RT = Ω









4. Based on an applied source voltage of #VAM# Vdc and circuit resistance of #RTC#Ω,

calculate the circuit current.

IT = mA

Recall Label for this Question: ITC


Value Calculation: #VAM# / #RTC# * 1000








3-94


5. Use the measured voltage drop of R1 to determine circuit current (IT = VR1 /R1).

IT (or IR1) = mA

Recall Label for this Question: ITVR1


Min/Max Value: (3.717) to (6.903)






6. Your calculated total circuit current is #ITC# mA. The circuit current based on the voltage

drop across R1 is #ITVR1# mA. Do the current values indicate that the same current flows

throughout a series circuit?

a. Yes. The current in a series circuit is the same throughout the circuit.

b. No. The current in a series circuit need not be the same throughout the circuit.

c. No. The current in a series circuit varies according to the values of the resistors in the string.


7. CM 2 is activated. Does the circuit modification cause total current to increase, decrease, or

remain the same as the unmodified total circuit current (#ITC# mA)?

a. The circuit current increased because circuit resistance decreased.

b. No change occurred in the circuit because circuit voltage did not change.

c. The circuit current decreased because circuit resistance increased.


8. CM 2 is still activated. The resistance of R2 is changed. What effect does this change have on

the circuit current?

a. None, since only one resistor is changed.

b. The circuit current must change.

c. None, until a matching voltage change is made.


3-95

REVIEW QUESTIONS


1. In a series circuit, the current is

a. greater in the larger resistors.

b. the same in all parts of the circuit.

c. greater when total resistance increases.

d. inversely proportional to the voltage source.


2. When you connect an ammeter into a dc circuit,

a. the ammeter is connected in series with the circuit.

b. polarity is not important.

c. the ammeter is connected in parallel with the circuit.

d. the RED lead is connected to the most negative point in the circuit.


CM 2 is activated. Which component caused the circuit current to change?

a. R1 increased in value.

b. R2 increased in value.

c. R3 increased in value.

d. The voltage source decreased in value.


4. In this circuit, if R1 changed in value to 2 kΩ, the

a. current through R1 would be 5.3 mA.

b. total resistance would be 3620Ω.

c. total circuit current would be 4.3 mA.

d. current through R1 would be 3.9 mA.


5. An increase in the current of a series circuit can be caused by a

a. proportional increase in voltage and resistance.

b. voltage decrease and resistance increase.

c. resistance decrease.

d. voltage decrease.


3-96

CMS AVAILABLE

CM 2

FAULTS AVAILABLE

None


3-97

Exercise 3 – Voltage in a Series Resistive Circuit

EXERCISE OBJECTIVE

Determine the voltage in a series resistive circuit by using a formula. Verify results with a

multimeter.

EXERCISE DISCUSSION


Based on the figure, which statement properly relates the polarities of points A and B with

respect to circuit common?

a. Point A is positive and point B is negative.

b. Points A and B are positive.

c. Points A and B are negative.

EXERCISE PROCEDURE


2. Measure the applied voltage.

VA = Vdc

Recall Label for this Question: VAMM


Min/Max Value: (14.55) to (15.45)






3-98


3. Measure the voltage drops of R1, R2, and R3. Input your voltage values with proper polarity

indications. Remember that the negative terminal of the voltage source is circuit common.

VR1 = Vdc



Min/Max Value: (3.724) to (6.916)






VR2 = Vdc



Min/Max Value: (4.466) to (8.294)






VR3 = Vdc


Nominal Answer: 3.3







4. In your series circuit, what is the relationship between the source voltage and the sum of the

string voltage drops? Refer to the data below.

a. The source voltage and each voltage drop are added to determine total voltage.

b. The source voltage equals the sum of the voltage drops.

c. The source voltage and each voltage drop are subtracted to determine total voltage.


3-99


5. Again measure the voltage drop of R1. This time, place the BLACK lead of your multimeter

at the top of R1. Input your voltage reading, including the sign (+ or –) of the voltage.

VR1 = Vdc

Recall Label for this Question: VR1MR

Nominal Answer: –5.32

Min/Max Value: (–6.916) to (–3.724)

Value Calculation: –5.320

Correct Tolerance Percent = false

Correct Minus Tolerance = 1.596

Correct Plus Tolerance = 1.596


6. Based on the last meter polarity indication, which statement applies to your circuit?

a. The voltage across R1 has doubled because #VR1M# Vdc and #VR1MR# Vdc indicate

different magnitudes of voltage drop.

b. The voltage across R1 is zero because #VR1M# Vdc and #VR1MR# Vdc cancel each other

when added.

c. The sign of the voltage drop is negative due to the multimeter connection. The

magnitude of the voltage drop does not change.


8. With respect to the established circuit common point, what is the expected polarity (+ or -) at

the junction of R1 and R2?

a. positive

b. negative


9. With respect to the established circuit common point, what is the expected polarity (+ or -) at

the top of R1?

a. positive

b. negative


10. With respect to the established circuit common point, what is the expected polarity (+ or –) at

the lower end of R3?

a. positive

b. negative


3-100


11. Connect the BLACK multimeter lead at the junction of R2 and R3. What is the indicated

voltage polarity at the top of R1?

a. positive

b. negative


What is the indicated polarity at the junction of R1 and R2?

a. positive

b. negative


What is the indicated polarity at the lower end of R3?

a. positive

b. negative


12. Based on your results, which statement best describes the effects of a change in circuit

reference point?

a. The expected and measured polarities agree.

b. The expected and measured polarities do not agree.

c. The polarities cannot agree because circuit common was changed.


13. Based on the voltage drops of R1, R2, and R3, what is the relationship between current and

resistance with respect to the magnitude of the voltage drop?

a. Based on Ohm's law, there is no direct relationship.

b. For a given circuit current, the greatest drop occurs across the lower value resistor.

c. For a given circuit current, the greatest drop occurs across the highest value resistor.


3-101

REVIEW QUESTIONS


1. In a series circuit, the voltage source

a. is equal to the sum of the voltages across the components.

b. is applied directly across each component.

c. applies different amounts of current through each component.

d. is always divided equally among all components.


2. Two 50Ω resistors are connected in series across a 10 Vdc source. The voltage drop of each

resistor is

a. 10V.

b. 7.5V.

c. 5V.

d. 2.5V.


3. In this circuit, CM 1 is activated. Which of the following is true?

a. R3 increased to 500Ω and circuit current decreased.

b. R2 decreased to 500Ω and circuit current increased.

c. R1 decreased to 500Ω and circuit current increased.

d. R1 increased to 500Ω and circuit current increased.


4. Refer to the figure above. CM 1 is still active. What is the total circuit current and voltage

across R2, respectively?

a. 6 mA and 0V

b. 6 mA and 7.8 Vdc

c. 0V and 6 mA

d. 0 mA and 0 V


5. When you connect a voltmeter in a F.A.C.E.T. series circuit, the

a. polarity is not important when measuring voltage.

b. meter is connected in series with the circuit.

c. negative lead is connected to the most positive end of the component.

d. negative lead is connected to the most negative end of the component.


3-102

CMS AVAILABLE

CM 1

FAULTS AVAILABLE

None


3-103

UNIT TEST



When you connect a voltmeter to read a dc voltage,

a. polarity is not important.

b. the voltmeter is connected in series with the circuit.

c. the voltmeter is connected across the component.

d. the common meter lead is connected to the most positive point in the circuit.


When a voltage is indicated at some point in the circuit, the voltage is actually

a. between that point and a reference point.

b. without reference to any other point.

c. between that point and the positive terminal of the source.

d. between that point and any other point.


In a series circuit, the current is

a. greatest in the highest value resistance.


c. the sum of the current in all components.

d. greatest in the lowest value resistance.


In a series circuit, the source voltage

a. is equal to the sum of the voltages across the components.

b. is applied directly across each component.

c. forces a different amount of current through each component.

d. is always divided equally among each component.


In a series circuit, the total resistance

a. is less than the resistance of any component.

b. is inversely proportional to the source voltage.

c. equals the sum of the individual resistances.

d. increases when the circuit current increases.


3-104


If the voltage source in the figure above is increased from 10V to 20V, then

a. the total resistance reduces to half of its original value.

b. the voltages across R1, R2, and R3 double.

c. the current through R1 and R2 doubles, and the current through R3 is cut in half.

d. there is no change in the circuit current.


In this circuit, if R3 increases from 1.5 kΩ to 3 kΩ, the

a. voltage across R3 increases to 6V.

b. circuit current decreases to 1.7 mA.

c. current through R2 increases to 2 mA.

d. voltage source increases to 15 Vdc.


A decrease of the current in a series circuit can be caused by a

a. voltage source increase.

b. resistance decrease.

c. resistance increase.

d. resistance voltage drop decrease.


The sum of series voltage drops

a. is less than the smallest voltage drop.

b. equals the average value of all the voltage drops.

c. equals the applied voltage.

d. is usually more than the applied voltage.


When the resistance of a series string decreases, the

a. individual resistor voltage drops increase.

b. total current increases.

c. applied voltage increases.

d. circuit current remains the same.


3-105

TROUBLESHOOTING


Measure the voltage drop of R1 and apply Ohm's law (IT = VR1 /R1) to determine circuit

current. HINT: Use the resistor color code chart to determine the value of R1.

IT = mA



Min/Max Value: (5.01 ) to (5.65 )






5. The faulty component in the SERIES circuit block is





Location: Troubleshooting page: ttrbb2, Question ID: trbb2a

Measure the voltage drop of R1 and apply Ohm's law (IT = VR1 /R1) to determine circuit

current. HINT: Use the resistor color code chart to determine the value of R1.

IT = mA



Min/Max Value: (5.01 ) to (5.65 )





Location: Troubleshooting page: ttrbb3, Question ID: trbb3

5. The faulty component in the SERIES circuit block is






3-106

CMS AVAILABLE

None

FAULTS AVAILABLE

Fault 1

Fault 2

DC Fundamentals Unit 8 – Parallel Resistive Circuits

3-107

UNIT 8 – PARALLEL RESISTIVE CIRCUITS

UNIT OBJECTIVE

Determine resistance, current, and voltage in a parallel resistive circuit by using a formula.

UNIT FUNDAMENTALS


Which description defines the current path of a parallel circuit?

a. The circuit current is identical through all components of the string.

b. Branch currents may differ for each circuit branch.

c. Branch current must be identical for each circuit branch.


In this circuit, which statement best describes the distribution of current?

a. The total circuit current is the same as either IR1 or IR2.

b. The currents through R1 and R2 are not equal because both resistances are equal.

c. The currents through R1 and R2 are equal because both resistances are equal.


In a two-branch parallel circuit, total source current equals 150 mA. If one branch current equals

100 mA, what is the value of the other branch current?

a. 50 mA

b. 150 mA

c. 250 mA

CMS AVAILABLE

None

FAULTS AVAILABLE

None


3-108

NEW TERMS AND WORDS

parallel circuit – a circuit with two or more components connected across one voltage source.

product-over-sum – mathematical method used to find equivalent circuit resistance in a parallel

circuit with two branches.

reciprocal method – a mathematical method used to find equivalent circuit resistance in a

parallel circuit with more than two branches.

EQUIPMENT REQUIRED



Multimeter


3-109

Exercise 1 – Resistance in a Parallel Circuit

EXERCISE OBJECTIVE

Determine the equivalent resistance in a parallel resistive circuit by using a formula. Verify

results with a multimeter.

EXERCISE DISCUSSION


A two-branch parallel circuit has resistances of 1000Ω and 2000Ω. Based on the product-over-

sum method, what is the circuit's equivalent resistance?

a. 6666Ω

b. 666Ω

c. 66.6Ω


In this circuit, if another resistor is added in parallel with R3, the equivalent resistance will

a. decrease.

b. not change.

c. increase.

EXERCISE PROCEDURE


2. Calculate the equivalent resistance of R1 and R2.

RE = Ω

Recall Label for this Question: R1R2EC


Min/Max Value: ( 1713) to ( 1893)






3-110


3. Measure your circuit's equivalent resistance, and compare it to the calculated value of

#R1R2EC#Ω. Does your comparison indicate that the product-over-sum method applies to a

two-branch parallel circuit?

a. yes

b. no

c. No, the product-over-sum method applies to three-branch circuits only.


4. If you add R3 to the circuit, RE will

a. increase.

b. not change.

c. decrease.


RE = Ω

Recall Label for this Question: R123EC


Min/Max Value: ( 1238) to ( 1368)






7. Based on your circuit measurements and observations, RE in a parallel resistive circuit is

a. greater than the value of the lowest resistive branch.

b. equal to the value of the lowest resistive branch.

c. less than the value of the lowest resistive branch.


3-111

REVIEW QUESTIONS


1. With two resistances connected in parallel,

a. the current through each is always the same.

b. the voltage across each is different.

c. their combined resistance is less than the individual resistor values.

d. their combined resistance is more than the individual resistor values.


2. If one 5 kΩ and two 10 kΩ resistors are connected in parallel, what is the RE of the circuit?

a. 1.5 kΩ

b. 2.5 kΩ

c. 5 kΩ

d. 10 kΩ


3. The product-over-sum method is used to find RE in

a. any resistive circuit.

b. any series resistive circuit.

c. a parallel circuit with two branches.

d. a parallel circuit with more than two branches.


4. Connect the circuit shown. CM 7 is activated. Using an ohmmeter, determine what

modification was made to the circuit?

a. The modification cannot be determined.

b. The value of R1 increased.

c. The value of R2 increased.

d. The value of R3 increased.


5. With 20 Vdc applied across five 30Ω resistors in a parallel circuit, the equivalent resistance

equals

a. 6Ω.

b. 10Ω.

c. 30Ω.

d. 150Ω.


3-112

CMS AVAILABLE

CM 7

FAULTS AVAILABLE

None


3-113

Exercise 2 – Voltage/Current in a Parallel Circuit

EXERCISE OBJECTIVE

Determine voltage and current flow in a parallel circuit by using a formula. Verify results with a

multimeter.

EXERCISE DISCUSSION


In a parallel circuit, what is the relationship between the voltage source and the circuit branches?

a. The voltage source is divided by the number of circuit branches.

b. The voltage source is applied across each branch and is common to all the branches.

c. A separate but common voltage source is required for each parallel branch circuit.


In this circuit, what defines the value of IT?

a. IT = IR1 + IR2 + IR3

b. IT = IR1 – IR2 – IR3

c. IT cannot be defined because of the common voltage source.


Total circuit current equals

a. the sum of the branch currents.

b. the source voltage divided by the equivalent circuit resistance.



3-114

EXERCISE PROCEDURE


2. On your circuit, measure the voltage across each branch. Based on your meter indications,

which statement is correct?

a. The branch voltages and source voltage are all equal.

b. The branch voltages are equal, but the source voltage is a different value.

c. None of the branch voltages equals the source voltage.


IT = mA









IR1 = mA

Recall Label for this Question: IR1M

Nominal Answer: 1.5







IR2 = mA



Min/Max Value: (4.774) to (8.866)






3-115


IR3 = mA



Min/Max Value: (2.233) to (4.147)






7. Based on your data, what is the relationship between total current and the branch currents of

your parallel circuit?

a. The sum of the branch currents does not equal the total current.

b. The sum of the branch currents is about equal to the total current.

c. Placing R3 into the circuit did not change the total circuit current but did change the currents

of the other branches.


IT = mA

Recall Label for this Question: ITCM5


Min/Max Value: (11.27) to (20.93)






9. Based on an unmodified circuit current of #ITM# mA and a modified circuit current of

#ITCM5# mA, the equivalent resistance of the circuit

a. increased.

b. did not change.

c. decreased.


3-116


10. CM 5 caused an increase in total circuit current. If branch R1 accounted for the entire

current change, R1 must

a. decrease in value.

b. be taken out of the circuit.

c. increase in value.


11. Given the currents below and the equation IT = IR1 + IR2 + IR3, what is the value of IR1?

IT = #iTCM5# mA

IR2 = #iR2M# mA

IR3 = #iR3M# mA

a. about #0 + iTCM5 – ( IR2M + IR3M ) # mA

b. about 1.5 mA

c. cannot be determined

REVIEW QUESTIONS


1. In a parallel circuit, the current

a. is greater in the branch with the highest resistance.

b. in each branch is added together to give total current.

c. is the same in all parts of the circuit.

d. is inversely proportional to the source voltage.


2. In a parallel circuit, the voltage source

a. is applied directly across each branch.

b. equals the sum of the voltages across each branch.

c. is inversely proportional to each branch resistance.

d. causes the same amount of current to flow in each branch.


3. A parallel circuit with 20 Vdc applied across two branches has a total current of 5A. One

branch circuit resistance equals 5Ω. The other branch resistance equals

a. 5Ω.

b. 20Ω.

c. 25Ω.

d. 100Ω.


3-117


4. CM 6 is activated. Measure the individual branch currents to determine what modification

was made to the circuit.

a. R1 decreased.

b. R2 increased.

c. R3 increased.

d. RT stayed the same.


5. CM 5 is activated. Measure the individual branch currents to determine what modification

was made to the circuit.

a. The circuit is operating properly.

b. R3 is open.

c. R2 is open.

d. R1 decreased in value.

CMS AVAILABLE

CM 5

CM 6

FAULTS AVAILABLE

None


3-118

UNIT TEST



When resistance is added in parallel, total current

a. has no relationship to the increase in resistance.

b. decreases.

c. increases.

d. remains the same.


When two resistances are connected in parallel,

a. the current through each is the same.

b. the voltage across each is the same.

c. their combined resistance equals the sum of the individual values.

d. each must have the same resistance values.


Branch voltage in a parallel circuit is

a. equal to the source voltage.

b. equal to the sum of the branch voltages.

c. equally divided among each branch.

d. inversely proportional to the branch resistance.


Current in a parallel circuit is

a. greatest in the branch with the highest resistance.


c. inversely proportional to the source voltage.

d. equal to the sum of all branch currents.


In a parallel circuit, equivalent resistance is

a. equal to the product of the branch resistances.

b. equal to the sum of the branch resistances.

c. less than the resistance of any branch.

d. greater than the resistance of any branch.


3-119


With three 4.5 kΩ and one 1.5 kΩ resistors in parallel, the equivalent resistance is

a. 750Ω.

b. 75Ω.

c. 7.5Ω.

d. 0.75Ω.


The total current for the circuit is

a. 6.1 mA.

b. 9.1 mA.

c. 13.3 mA.

d. 28.5 mA.


If a 700Ω resistor were added in parallel with the resistors above, the equivalent resistance would

be

a. 350Ω.

b. 503Ω.

c. 702Ω.

d. 1.5 kΩ.


If the voltage source of the circuit shown above were increased to 30V,

a. IR1 would be 20 mA.

b. IR2 would be 13.6 mA.

c. IR3 would be 9.1 mA.



When you connect a multimeter in a parallel circuit to measure the total circuit current,

a. polarity is not important.

b. the meter is connected in series between the source voltage and the first branch.

c. the meter is connected in series with the first branch.

d. the meter is connected in series between the first and second branches.


3-120

TROUBLESHOOTING

Location: Troubleshooting page: strba2, Question ID: trba2a

Measure total circuit current.

IT = mA



Min/Max Value: (10.88) to (12.26)





Location: Troubleshooting page: strba3, Question ID: trba3

5. The faulty component in the PARALLEL circuit block is



c. R2, which is above its specified value.

d. R3, which is above its specified value.

Location: Troubleshooting page: strbb2, Question ID: trbb2a

Measure total circuit current.

IT = mA



Min/Max Value: (10.88) to (12.26)





Location: Troubleshooting page: strbb3, Question ID: trbb3

5. The faulty component in the PARALLEL circuit block is



c. R2, which is above its specified value.

d. R3, which is above its specified value.


3-121

CMS AVAILABLE

None

FAULTS AVAILABLE

Fault 4

Fault 5


3-122

DC Fundamentals Unit 9 – Series/Parallel Resistive Circuits

3-123

UNIT 9 – SERIES/PARALLEL RESISTIVE CIRCUITS

UNIT OBJECTIVE

Find values for resistance, voltage, and current in a series/parallel resistive circuit.

UNIT FUNDAMENTALS


In this circuit, which of the following defines the relationship of RE to the circuit components?

a. RT and RE are equal and defined by the product- over-sum relationship of R2 and R3.

b. RT is defined by R1 + RE. RE is defined by the product- over-sum relationship of R2

and R3.

c. RT = R1 + R2 + R3. RE equals the total resistance minus R1.


Which statement best describes total circuit current distribution?

a. Total current flows through R1 and divides between R2 and R3.

b. Total current flows through R2 and through R3.

c. The current through R1 equals the difference between IR2 and IR3.


Which statement best describes the circuit's voltage distribution?

a. Applied voltage equals the sum of the voltage drops of R1 and RE.

b. Each voltage drop must equal the value of the applied voltage.

c. The voltage drops of the parallel elements must equal the voltage across R1.

CMS AVAILABLE

None

FAULTS AVAILABLE

None


3-124

NEW TERMS AND WORDS

None

EQUIPMENT REQUIRED



Multimeter


3-125

Exercise 1 – Resistance in a Series/Parallel Circuit

EXERCISE OBJECTIVE

Determine the total equivalent resistance of a series/parallel circuit. Verify results with a

multimeter.

EXERCISE DISCUSSION


To determine the equivalent resistance of a parallel circuit branch with more than two resistors of

different values

a. use the reciprocal method.

b. add the values of the resistors.

c. divide the value of one resistor by the number of resistors in the branch.

EXERCISE PROCEDURE


RE = Ω

Recall Label for this Question: REC








RT = Ω









3-126


RE = Ω

Recall Label for this Question: REM








5. Measure the total resistance of your circuit.

RT = Ω

Recall Label for this Question: RTM








6. How did you determine the total resistance of your circuit?

a. You combined R2 and R3 and added the results to R1. Your measured and calculated

results were about the same.

b. You combined R1 and R2 and added the results to R3. Your measured and calculated results

were about the same.

c. You used your meter to measure total circuit resistance and determined that calculated and

measured values cannot be compared.


7. In this circuit, R4 is added to the parallel network. What is the effect on RE?

a. RE increases.

b. RE does not change.

c. RE decreases.


3-127


8. In this circuit, R4 is added to the parallel network. What is the effect on RT?

a. RT increases.

b. RT does not change.

c. RT decreases.


9. CM 12 is activated. The CM causes total circuit resistance to

a. increase because a resistor is added in parallel with R2.

b. remain the same because the CM is not added in series to the parallel branch.

c. decrease because a resistor is added in parallel with R2.


10. Does adding resistance in parallel with your circuit increase or decrease the total resistance of

the series/parallel circuit?

a. increase

b. decrease


RT = Ω

Recall Label for this Question: RTCM13








12. The unmodified total resistance of your circuit is #RTM#Ω. With CM 13 activated, the total

resistance is #RTCM13#Ω. Based on your observation, which statement is correct?

a. The modification increases total resistance; therefore, resistance is added in series with

the overall circuit.

b. The modification increases total resistance; therefore, resistance is added in parallel with the

overall circuit.

c. The modification decreases the equivalent resistance of R2 R3.


3-128

REVIEW QUESTIONS


1. A series/parallel resistive circuit is

a. made up of series and parallel components connected together.

b. a group of series circuits and parallel circuits connected together.

c. made up of series and parallel circuits connected together.



2. To find total resistance in a series/parallel resistive circuit, reduce the

a. parallel branch to an equivalent value and add it to the value of the series branch.

b. series branch to an equivalent value and add it to the resistors in the parallel branch.

c. parallel branch to an equivalent value and use the product-over-sum method with the series

branch.

d. series branch to an equivalent value and use the reciprocal method with the series branch.


3. What would cause the actual measured value of total circuit resistance to vary from the

calculated value?

a. the tolerance of the multimeter

b. the tolerance of circuit components

c. an uncalibrated ohmmeter



4. If three 10 kΩ resistors are connected together to form a series/parallel circuit, what is the RT

of the circuit?

a. 30 kΩ

b. 15 kΩ

c. 10 kΩ

d. 5 kΩ


3-129


5. In the SERIES/PARALLEL CIRCUIT circuit block, CM 14 is activated. Measure resistance

to determine what modification was made to the circuit.

a. A 200Ω resistor was placed in series with R2.

b. A 770Ω resistor was placed in series with R1.

c. A 4.7 kΩ resistor was placed in series with R3.

d. A 7 kΩ resistor was added to the parallel branch.

CMS AVAILABLE

CM 12

CM 13

CM 14

FAULTS AVAILABLE

None


3-130

Exercise 2 – Voltage in a Series/Parallel Circuit

EXERCISE OBJECTIVE

Find voltage in a series/parallel circuit by using Ohm's law. Verify results with a multimeter.

EXERCISE DISCUSSION


In this circuit, the voltage across R2 (VR2) equals

a. VR3.

b. VR1.

c. VA.


Which statement defines the proper voltage relationships of this circuit?

a. VA = VR3 + VBC

b. VA = VR1 + VR2

c. VA = VR1 + VR2 + VBC

EXERCISE PROCEDURE


VA = Vdc



Min/Max Value: (14.55) to (15.45)






3-131


VR1 = Vdc



Min/Max Value: (3.942) to (4.818)







VR2 = Vdc



Min/Max Value: (9.558) to (11.68)







VR3 = Vdc



Min/Max Value: (9.558) to (11.68)






6. Based on your data below, which statement properly relates the voltage drops of your circuit?

a. The voltage drops are not related because of the series/parallel combination.

b. The voltage drop of R1 indicates a circuit problem because its value is not equal to that of

VR2 or VR3.

c. The voltage drops are correct because the sum of the series and parallel combination

voltage drops equals VA.


3-132


7. To calculate the voltage drop of R1,

a. multiply either IR2 or IR3 with the value of R1.

b. subtract the sum of VR1 and VR2 from VA.

c. multiply IT by the value of R1.


What is the relationship of the circuit voltages with resistor R4 added?

a. VA = VR1 + VRE + VR4

b. VA = VR1 + VR4

c. VR1 = VR3 and VR2 = VR4


9. CM 12 is still activated. VR4 equals

a. IR4 x R4.

b. IT x R4.

c. (IR2 + IR3) x R4.


10. CM 12 is still activated. What are the voltage drops of R2 and R3?

a. about 15 Vdc

b. about 4.45 Vdc

c. about 9.7 Vdc


3-133

REVIEW QUESTIONS


1. What is Ohm's law for finding voltage in a circuit?

a. E = I/R

b. E = IR

c. E = R/I

d. E = E/RI


2. In a series/parallel circuit consisting of three equal 5 kΩ resistors, the voltage drop is

a. greatest across the parallel branch.

b. greatest across the series branch resistor.

c. equal across all the branches.



3. What information do you need to calculate the voltage drop across a parallel branch of a

series/parallel circuit?

a. total circuit current (IT) and equivalent resistance (RE)

b. equivalent resistance (RE)

c. applied voltage (VA)



4. In this circuit, what would be the effect if R3 were shorted?

a. VR1 would decrease.

b. VR2 would increase.

c. VRE would increase.

d. VR1 would equal VA.


5. On the SERIES/ PARALLEL CIRCUIT circuit block, connect the circuit shown. CM12 is

activated. What modification was made to the circuit?

a. A 600Ω resistor was placed in the parallel branch.

b. A 1 kΩ resistor was placed in parallel with R1.

c. A 2.7 kΩ resistor was placed in parallel with R2.

d. A 4.7 kΩ resistor was placed in parallel with R3.


3-134

CMS AVAILABLE

CM 12

FAULTS AVAILABLE

None


3-135

Exercise 3 – Current in a Series/Parallel Circuit

EXERCISE OBJECTIVE

Find the value of current flow in a series/parallel circuit by using Ohm's law. Verify results with

a multimeter.

EXERCISE DISCUSSION

No Questions

EXERCISE PROCEDURE


IT = mA

Recall Label for this Question: ITDR1


Min/Max Value: (11.94) to (14.6 )






IR2 = mA

Recall Label for this Question: IR2DR2


Min/Max Value: (7.965) to (9.735)






3-136


IR3 = mA

Recall Label for this Question: IR3DR3


Min/Max Value: (3.987) to (4.873)






4. Based on your data below, which of the following describes the current distribution of your

circuit?

a. IR3 = IR2 = IR1

b. IT – IR1 = IR2 + IR3

c. IT = IR1 = IR2 + IR3


5. CM 12 is activated. Determine the currents in your circuit. Based on your measurements,

which statement best applies to your circuit?

a. In the parallel branch, highest current flows through the path with highest conductance.

b. IT = IR1 = IR2 + IR3 + IR4



6. CM 12 is still activated. Based on your measurements, CM 12 causes total current to

a. increase because circuit resistance decreases.

b. remain the same, although resistance changes.

c. decrease because circuit resistance decreases.


7. CM 12 is still activated. The modification caused total circuit current to increase. Based on

Ohm's law, total circuit resistance

a. must increase.

b. does not change.

c. must decrease.


3-137

REVIEW QUESTIONS


1. Current flow in a series/parallel circuit

a. is determined by the total circuit resistance and applied voltage.

b. is determined by the resistors in each parallel branch.

c. divides in each series branch circuit.

d. equals the sum of the current in each circuit component.


2. In a series/parallel resistive circuit, what would cause one leg of a parallel branch to have a

lower current flow than another leg in that same parallel branch?

a. a higher resistance

b. a lower resistance

c. an increase in current in one leg

d. All branches have equal current flow.


3. In this circuit, if R3 were shorted, IT would

a. remain the same.

b. decrease.

c. increase.

d. not flow.


4. In this circuit, if R2 were open, IT would

a. remain the same.

b. increase.

c. decrease.

d. vary.


5. CM 15 is activated in this circuit. What modification was made?

a. A 10Ω resistor was placed in parallel with R3.

b. A 1 kΩ resistor was placed in series with R1.

c. R3 was shorted.

d. R2 was opened.


3-138

CMS AVAILABLE

CM 12 TOGGLE

CM 12

CM 15

FAULTS AVAILABLE

None


3-139

UNIT TEST



A series/parallel equivalent resistive circuit appear as what kind of load configuration to a power

source?

a. series/parallel resistors

b. single resistor

c. two series resistors

d. two parallel resistors


The first step in calculating the total resistance of a series/parallel resistive circuit is to

a. find a single equivalent resistance.

b. combine all the series voltages.

c. find the equivalent resistance of the parallel branch.

d. combine all the parallel voltages.


If R3 opened, total circuit resistance would be

a. 1530Ω.

b. 330Ω.

c. 800Ω.

d. 1130Ω.


The reciprocal method for finding an equivalent resistance is usually used in a

a. parallel branch with more than two resistors.

b. parallel branch with two resistors.

c. series/parallel branch with more than two resistors.

d. series branch with more than two resistors.


Source voltage in a series/parallel resistive circuit is

a. increased as total resistance increases.

b. distributed across each circuit component.

c. determined by the product-over-sum method.

d. equal to the voltage drop of the parallel branch.


3-140


If R1 shorted, the

a. circuit current would increase.

b. current through R2 would decrease.

c. current through R3 would decrease.

d. circuit current would remain the same.


During a circuit check of this circuit, you find that VRE is 13.18V. The probable cause of the

reading is that

a. R2 is open.

b. R3 is open.

c. R1 is shorted.

d. VA = 13.18V.


To determine the voltage drop of R1, using minimum steps, you need to know

a. total circuit current.

b. parallel branch equivalent resistance.

c. total circuit resistance.



In the parallel branch of a series/parallel resistive circuit, total current equals the sum of the

currents flowing through each leg, found by

a. adding the current through each series resistor.

b. dividing the voltage across the branch by the resistance in each leg.

c. multiplying the voltage across the branch by the resistance in each leg.

d. dividing total resistance by the applied voltage.


In this circuit, IT = 9.8 mA, VRE = 11.76V, and VR1 = 3.23V. What is wrong with the circuit?

a. R3 is open.

b. R2 is open.

c. R1 is shorted.

d. nothing


3-141

TROUBLESHOOTING


If your source voltage is within 15 Vdc, +/–3%, continue with the voltage drop of R3. If the

source voltage is outside the specified range, ask your instructor for help before you continue.

Measure the voltage drop of R3.

VR3 = Vdc



Min/Max Value: (10.18) to (11.02)






5. The faulty component in the SERIES/PARALLEL circuit block is

a. RE, which increased in value.

b. R2, small increase in value.

c. R1, large increase in value.

d. R2, small decrease in value.


If your source voltage is within 15 Vdc, +/–3%, continue with the voltage drop of R3. If the

source voltage is outside the specified range, ask your instructor for help before you continue.


VR3 = Vdc



Min/Max Value: (10.18) to (11.02)






3-142


5. The faulty component in the SERIES/PARALLEL circuit block is

a. RE, which increased in value.

b. RE, which decreased in value.

c. R1, which increased in value.

d. R2, which decreased in value.

CMS AVAILABLE

None

FAULTS AVAILABLE

Fault 8

Fault 9

DC Fundamentals Unit 10 – Power in DC Circuits

3-143

UNIT 10 – POWER IN DC CIRCUITS

UNIT OBJECTIVE

Determine power in series, parallel, and series/parallel resistive circuits.

UNIT FUNDAMENTALS


If a circuit dissipates 200W of power and draws 2A of current, what is the required source

voltage?

a. 400V

b. 100V

c. 25V

CMS AVAILABLE

None

FAULTS AVAILABLE

None

NEW TERMS AND WORDS

power – The measure of work done within a specific time.

dissipates – The act of a resistor giving off heat as current flows through it.

EQUIPMENT REQUIRED



Multimeter


3-144

Exercise 1 – Power in a Series Resistive Circuit

EXERCISE OBJECTIVE

Determine the power dissipated in a series resistive circuit by using a power formula. You will

verify your results with a multimeter.

EXERCISE DISCUSSION

No Questions

EXERCISE PROCEDURE


VA = Vdc



Min/Max Value: (–19.5) to (–10.5)

Value Calculation: –15





IT = mA



Min/Max Value: (–5.5) to (–4.5)






3-145


PT = mW

Recall Label for this Question: PTC


Value Calculation: #VAM# * #ITM#





4. Measure the voltage drop of R1, and calculate the power dissipation of R1.

PR1= mW

Recall Label for this Question: PR1C








5. Calculate the power dissipation in R2 by using the total current, #ITM# mA, and the power

formula I2 x R2.

PR2= mW

Recall Label for this Question: PR2C


Value Calculation: (#ITM#^2)*2








3-146


6. Based on your circuit data and power calculations, the power supplied by the source is

NOTE: Data values are not exact due to circuit and measurement tolerances.

a. equal to PT + PR1 + PR2.

b. equal to PT – (PR1 + PR2).

c. the total circuit power and is equal to PR1 + PR2.


7. In this circuit, PR1

a. equals VR1 x IT, IT2 x R1, or VR1

2/R1.

b. can be determined only if IR1 is known.

REVIEW QUESTIONS


1. The power dissipated in the form of heat by a resistor is supplied by the

a. resistor.

b. circuit components.

c. source voltage.

d. current through the resistor.


2. The total power in a circuit with a voltage source of 20 Vdc and a total current of 80 mA is

a. 1.6 mW.

b. 16 mW.

c. 160 mW.

d. 1600 mW.


3. Locate the POWER circuit block, and connect the circuit shown. CM 17 is activated.

Determine the total power dissipated by the circuit when S1 is in the A position.

a. 69 mW

b. 75 mW

c. 89 mW

d. 93 mW


3-147


4. In this circuit, if R1 changed value to 2 kΩ, how much power would it dissipate?

a. 28 mW

b. 56.25 mW

c. 22 mW

d. 18.125 mW


5. Two 10 kΩ resistors connected in series across a power source of 20 Vdc will each dissipate

a power of

a. 1 mW.

b. 5 mW.

c. 10 mW.

d. 20 mW.

CMS AVAILABLE

CM 17

FAULTS AVAILABLE

None


3-148

Exercise 2 – Power in a Parallel Resistive Circuit

EXERCISE OBJECTIVE

Determine the power dissipated in a parallel resistive circuit by using a formula. Verify results

with a multimeter.

EXERCISE DISCUSSION

No Questions

EXERCISE PROCEDURE


PR2 = mW

Recall Label for this Question: PR2


Min/Max Value: (24.75) to (31.51)






3. Use the parallel branch voltage drop (VRE) to calculate the power dissipation in R3.

PR3 = mW



Min/Max Value: (24.75) to (31.51)






3-149


4. Based on your circuit data, what is the total power (PRE) dissipated by the parallel branch of

your circuit?

PR2 = #PR2# mW PR3 = #PR3# mW

a. PRE = PR1 + PR2 + PR3

b. PRE = PR2 + PR3

c. PRE = PT + PR2 + PR3


5. Move S1 from position A to position B. What is the relationship between R4 and R2 R3?

a. The resistance value of R4 equals the total circuit resistance.

b. R4 has no relationship to R2 R3.

c. The resistance value of R4 equals the equivalent resistance of R2 R3.


6. Measure the voltage drop of R4. Use this value to calculate the power dissipation

of R4.

PR4 = VR4 2/R4 = mW



Min/Max Value: (49.5) to (63)






7. Based on your circuit calculations, can the power dissipated in the parallel branch be

duplicated by an equivalent resistance?

PR2 = #PR2# mW

PR3 = #PR3# mW

PR4 = #PR4# mW

a. Yes. The power dissipated in a parallel circuit can be duplicated by a resistance

equivalent to that of the parallel circuit.

b. No. A single resistor cannot dissipate the power of a two-branch parallel circuit.

c. Yes. The dissipated power can be duplicated provided that the value of the equivalent

resistance is made double that of the parallel circuit.


3-150

REVIEW QUESTIONS


1. For a given parallel circuit, total power

a. equals the product-over-sum value.

b. cannot be found unless a source voltage is given.

c. equals the sum of the power dissipated in each leg.

d. must be the same in each leg.


2. If the current through a given resistor increases by 4.5, the power dissipation will

a. increase by 2.025.

b. increase by 20.25.

c. decrease by 2.025.

d. decrease by 20.25.


3. Which statement is true of the parallel circuit shown?

a. Maximum power and maximum current occur in R2.

b. Maximum power and maximum current occur in R4.

c. Power will divide evenly in each leg.

d. Because this is a parallel circuit, power is the same for each resistor.


4. On the POWER circuit block, place S1 in the A position. CM 16 is activated. Power

dissipation for R2, R3, and RCM is

a. PR2 = PR3 = 12.5 mW, PRCM = 25 mW

b. PR2 = PR3 = 12.5 mW, PRCM = 12.5 mW

c. PR2 = PR3 = 25 mW, PRCM = 25 mW

d. PR2 = PR3 = 25 mW, PRCM = 12.5 mW


5. CM 16 is activated to add a 1000Ω resistor (RCM) to the parallel branch. CM 16

a. increased the power dissipation of R2 and R3.

b. decreased the power dissipation of R2 and R3.

c. has no effect on the power dissipation of R2 and R3.

d. increased the power dissipation of the parallel branch.


3-151

CMS AVAILABLE

CM 16

CM 16 TOGGLE

FAULTS AVAILABLE

None


3-152

Exercise 3 – Power in a Series/Parallel Circuit

EXERCISE OBJECTIVE

Determine the power dissipated in a series/parallel resistive circuit by using a power formula.

Verify results with a multimeter.

EXERCISE DISCUSSION

No Questions

EXERCISE PROCEDURE


IT = mA

Recall Label for this Question: IT3DR1


Min/Max Value: (–8.25) to (–6.75)

Value Calculation: –7.500





3. Measure the value of your circuit source voltage.

VA= Vdc

Recall Label for this Question: VA3


Min/Max Value: (–15.6) to (–14.4)






3-153


4. Based on a source voltage of #VA3# Vdc and a circuit current of #IT3DR1# mA, what is the

total power dissipation of your circuit?

PT= mW

Recall Label for this Question: PT3


Value Calculation: (#VA3#*#IT3DR1#)





PR1 = mW

Recall Label for this Question: P3R1C


Min/Max Value: (48.16) to (63.84)






6. Determine the power dissipation in R2.

PR2 = mW



Min/Max Value: (24.08) to (31.92)









3-154


7. Determine the power dissipation in R3.

PR3 = mW



Min/Max Value: (24.08) to (31.92)






8. Based on your data, which statement applies to your circuit?

NOTE: Data values are not exact due to circuit and measurement tolerances.

a. The power dissipated in R2 and R3 equals the power dissipated in R1.

b. The total power dissipated by the circuit equals the sum of the power dissipated in each

circuit resistor.



10. Measure the voltage drop across the circuit load (across the parallel branch).

VRL = Vdc

Recall Label for this Question: V3L500

Nominal Answer: 5.0







11. CM 16 is deactivated. Measure the voltage drop across the circuit load.

VRL = Vdc

Recall Label for this Question: V3L1K

Nominal Answer: 7.5

Min/Max Value: (6.375) to (8.625)






3-155


12. Remove R3 from your circuit. Measure the voltage drop across the circuit load.

VRL = Vdc

Recall Label for this Question: V3L2K








13. Using your measured values of VL and PL = VL2/RL, calculate the power in milliwatts

dissipated in the load for the three different values of RL.

RL= 500 Ω PL= mW

Recall Label for this Question: PLL500


Value Calculation: ((#V3L500#^2)/500)*1000





RL= 1k Ω PL= mW

Recall Label for this Question: PLL1K


Value Calculation: (#V3L1K#^2)








3-156


RL= 2k Ω PL= mW

Recall Label for this Question: PLL2K


Value Calculation: (#V3L2K#^2)/2





14. Based on the data table, which statement applies to your circuit?

a. Maximum power cannot be transferred to the load because of R1.

b. Maximum power is transferred to the load when R1 and RL are not equal in value.

c. Maximum power is transferred to the load when R1 and RL are equal in value.

REVIEW QUESTIONS


1. The total power in a series/parallel circuit is

a. determined by the total circuit resistance.

b. determined by the resistors in each parallel branch.

c. determined by the resistors in each series branch.

d. equal to the sum of the power dissipated in each parallel branch.


2. The total power in a series/parallel circuit with a voltage source of 30V, a current of 20 mA

in the series branch, and a current of 10 mA in each of the two parallel branch circuits is

a. 1.5W.

b. 1.2W.

c. 0.9W.

d. 0.6W.





3-157


3. To determine total power in a three-branch parallel circuit,

a. use the product-over-sum method.

b. add individual branch power.

c. use the formula P = E/R.

d. find RE and multiply by VA.


4. On the POWER circuit block, place S1 in position B. CM 18 is activated. The total circuit

power dissipated equals 91.05 mW. You determine that a

a. 240Ω resistor is added in series with R1.

b. 240Ω resistor is added in parallel with R1.

c. 470Ω resistor is added in series with R4.

d. 470Ω resistor is added in parallel with R4.


5. Maximum power is transferred to the load when

a. ERL is greater than ERS.

b. ERL is equal to ERS.

c. ERL is less than ERS.

d. ERS is greater than ERL.

CMS AVAILABLE

CM 16

CM 18 TOGGLE

FAULTS AVAILABLE

None


3-158

UNIT TEST



The basic unit of measure of electric power is the

a. ampere.

b. watt.

c. volt.

d. ohm.


Electric power is the

a. same as electric pressure.

b. total number of electrons flowing in a circuit.

c. number of electrons passing a given point in one second.

d. rate of using or producing electric energy.


A 5Ω resistor connected to a 20 Vdc source will dissipate

a. 4W.

b. 5W.

c. 80W.

d. 100W.


In an electric circuit where the source voltage is 120V and the total circuit current is 5A, how

much power is being used?

a. 600W

b. 288W

c. 24W

d. 20W


Total power in a series circuit is equal to the

a. total resistance multiplied by the total current.

b. sum of the power dissipated by each resistor.

c. circuit voltage divided by the circuit current.

d. difference of the power dissipated by each resistor.


3-159


The total power in this circuit is

a. 50 mW.

b. 75 mW.

c. 300 mW.

d. 600 mW.


In this circuit, the power dissipated by R1 is

a. 270 mW.

b. 333 mW.

c. 423 mW.

d. 600 mW.


The power used in the series branch (R1 and R2) is

a. 50 mW.

b. 100 mW.

c. 150 mW.

d. 300 mW.


R3 dissipates how many watts?

a. 0.0681

b. 0.0833

c. 68.1

d. 83.3


The total circuit power is

a. 50 mW.

b. 100 mW.

c. 150 mW.

d. 300 mW.


3-160

TROUBLESHOOTING


Measure the voltage drop (VDROP) of R1 or RE.

VDROP = Vdc


Nominal Answer: 7.5







5. The faulty component in the POWER circuit block is

a. R1, which increased in value.

b. R1, which decreased in value.

c. R3, which decreased in value.

d. R4, which increased in value.


Measure the voltage drop (VDROP) of R1 or RE.

VDROP = Vdc


Nominal Answer: 7.5







5. The faulty component in the POWER circuit block is



c. R3, which decreased in value.

d. R4, which increased in value.


3-161

CMS AVAILABLE

None

FAULTS AVAILABLE

Fault 10

Fault 11


3-162

DC Fundamentals Unit 11 – Potentiometers and Rheostats

3-163

UNIT 11 – POTENTIOMETERS AND RHEOSTATS

UNIT OBJECTIVE

Identify and demonstrate the use of a potentiometer and a rheostat.

UNIT FUNDAMENTALS


Which statement relates voltage and current to variable resistors?

a. Potentiometers control load current and rheostats control load voltage.

b. Potentiometers control load voltage and rheostats control load current.

c. Potentiometers and rheostats are identical; therefore, both control voltage or current.

CMS AVAILABLE

None

FAULTS AVAILABLE

None

NEW TERMS AND WORDS

potentiometer – A variable resistor connected with three terminals to provide a variable voltage.

rheostat – A variable resistor connected with only two terminals to provide a variable current.

taper – Variation in resistance of a variable resistor due to changes in the angle of shaft rotation.

linear – A change or control that varies at a uniform rate through the entire range of adjustment.

logarithmic – A change or control that varies at a different rate through its range of adjustment;

also called nonlinear.

EQUIPMENT REQUIRED

F.A.C.E.T. base unit DC FUNDAMENTALS circuit board

Multimeter


3-164

Exercise 1 – The Rheostat

EXERCISE OBJECTIVE

Vary current by using a rheostat. Verify results with a multimeter.

EXERCISE DISCUSSION


With R2 set to the full CW position, power dissipation in load R1 is

a. maximum.

b. 0W.

c. minimum.

Location: Exercise Discussion page: se1d6, Question ID: e1d6c

With R2 set to the full CCW position, power dissipation in load R1 is

a. maximum.

b. 0W.

c. minimum.


3-165

EXERCISE PROCEDURE


R1 = Ω



Min/Max Value: (773.5) to ( 1047)






3. On your circuit, measure the resistance of R2A at 50%.

R2A at 50% = Ω

Recall Label for this Question: R2AHM








4. On your circuit, measure the resistance of R2A at 100%.

R2A at 100% = Ω

Recall Label for this Question: R2AFM








3-166


5. Energize your circuit block. Measure the voltage of R1 with R2A set for 0% (VR2A is 0 Vdc

with R2A set for 0%).

VR1 = Vdc

Recall Label for this Question: vr1zm


Min/Max Value: (14.25) to (15.75)






6. Measure the voltage of R1, with R2A set for 50% (midpoint).

VR1 = Vdc

Recall Label for this Question: VR1HM


Min/Max Value: (5.706) to (6.974)






7. Measure the voltage of R2A, with R2A set for 50% (midpoint).

VR2 at 50% = Vdc

Recall Label for this Question: VR2HM


Min/Max Value: (7.794) to (9.526)






3-167

Location: Exercise Procedure page: se1p4, Question ID: e1p4g

8. Measure the voltage of R1, with R2A set for 100% (full value).

VR1 = Vdc

Recall Label for this Question: VR1FM

Nominal Answer: 4.1






Location: Exercise Procedure page: se1p4, Question ID: e1p4i

9. Measure the voltage of R2A, with R2A set for 100% (full value).

VR2 at 100% = Vdc

Recall Label for this Question: VR2FM








10. Based on your data, circuit

a. voltages change because the rheostat affects total resistance and current.

b. voltages change because the potentiometer affects only circuit current.

c. current does not change; only resistance and voltage change.


11. In your circuit, a CW shaft rotation of R2A

a. decreases total resistance and decreases circuit current.

b. increases total resistance but does not affect circuit current.

c. increases total resistance and decreases circuit current.


12. In your circuit, when the value of R2A is over 910 ohms, rheostat power dissipation is:

a. not affected by the value of R2A.

b. inversely related to the value of R2A.

c. directly related to the value of R2A.


3-168


13. Which rheostat setting produces the maximum power dissipation in the circuit load?

a. maximum CW (maximum rheostat resistance)

b. maximum CCW (minimum rheostat resistance)

c. a midpoint setting of the rheostat

REVIEW QUESTIONS


1. A rheostat in an electrical circuit primarily controls the load

a. voltage.

b. current.

c. resistance.



2. When using a carbon-composition pot as a rheostat, you should

a. connect it in series.

b. connect it in parallel.

c. connect only the two end terminals.

d. use CCW rotation to decrease circuit current.


3. In this circuit, with R2A set at 50%, total circuit resistance is

a. 3410Ω.

b. 2500Ω.

c. 2160Ω.

d. 1250Ω.


4. In this circuit, with R2 set at 1200Ω, the load current is

a. 4.54 mA.

b. 6.25 mA.

c. 7.89 mA.

d. 8.33 mA.


3-169


5. In this circuit, if an ammeter were connected between R1 and R2, how much current would be

indicated if R2 were set to the maximum CCW position?

a. 16.66 mA

b. 8.33 mA

c. 6.25 mA

d. 5.68 mA

CMS AVAILABLE

None

FAULTS AVAILABLE

None


3-170

Exercise 2 – The Potentiometer

EXERCISE OBJECTIVE

Vary circuit voltage by using potentiometers with different tapers. Verify results with a

multimeter.

EXERCISE DISCUSSION


When compared to an unloaded potentiometer circuit, a loaded pot circuit

a. increases the maximum available output voltage.

b. has no effect on the maximum available output voltage.

c. decreases the maximum available output voltage.

EXERCISE PROCEDURE


4. Based on a comparison between your readings and the graph data, R2A has a

a. log taper.

b. combined linear/log taper.

c. linear taper.


5. Based on a comparison between your readings and the graph data, R2B has a

a. log taper.

b. combined linear/log taper.

c. linear taper.


8. Based on your comparison of circuit voltage and the voltage graph, R2A generates

a. a nonlinear load voltage.

b. a linear load voltage.

c. linear and nonlinear load voltage.


3-171


9. Based on your comparison of circuit voltage and the voltage graph, R2B generates

a. a nonlinear load voltage.

b. a linear load voltage.

c. linear and nonlinear load voltages.


10. Does the change in load voltage (for R2A and R2B) follow the same taper produced by shaft

rotation?

a. No. Pot taper and load voltage do not follow each other.

b. The data is inconclusive.

c. Yes. Pot taper and load voltage follow each other.


11. Which variable resistor provides a more precise voltage adjustment at the load for low angles

of shaft rotation?

a. R2A does because most of the voltage change occurs over the entire resistive element of the

pot.

b. Both variable resistors provide the same precision because change occurs over the entire

resistive element of the pot.

c. R2B does because a small change occurs over a large portion of the resistive element of

the pot.


13. CM 4 is activated. The drop in voltage indicates that the CM

a. increased the circuit loading.

b. did not affect the circuit loading.

c. decreased the circuit loading.


3-172

REVIEW QUESTIONS


1. In an electrical circuit, a potentiometer primarily provides a variable

a. voltage.

b. current.

c. resistance.

d. power source.


2. An S taper potentiometer provides what percentage of total resistance at what percentage of

shaft rotation?

a. 10%, 50%

b. 20%, 25%

c. 50%, 50%

d. 70%, 75%


3. A Z taper potentiometer provides what percentage of total resistance at what percentage of

shaft rotation?

a. 5%, 25%

b. 10%, 50%

c. 70%, 75%

d. 85%, 100%


4. In this circuit, what is the maximum output voltage available at R2B?

a. 11V

b. 10.68V

c. 8.68V

d. 3.42V


5. Set R2A to the maximum CW position. R3 is not connected to the circuit. Your

measurements across R2A indicate that

a. R3 has a 4.7 kΩ resistor in parallel.

b. R3 has a 2.4 kΩ resistor in series.

c. R2A has a 4.7 kΩ resistor in parallel.

d. R2A has a 2.4 kΩ resistor in parallel.


3-173

CMS AVAILABLE

CM 4 TOGGLE

CM 3

FAULTS AVAILABLE

None


3-174

UNIT TEST



A rheostat used in high power circuits is made of a

a. carbon film element.

b. carbon composition element.

c. resistive wire element.

d. resistive film element.


A rheostat in an electrical circuit

a. controls the load current.

b. is connected in parallel with the load.

c. controls the load resistance.

d. is connected using the wiper terminal to control the output.


Increasing the loading of a potentiometer circuit

a. has no effect on the output voltage.

b. can cause the output voltage to decrease.

c. can cause the output voltage to increase.

d. will reduce the output voltage by 10%.


The taper of a potentiometer is the

a. amount of resistance available at the output.

b. degree of shaft rotation.

c. ratio of output voltage to input voltage.

d. relationship of resistance to shaft rotation.


An S taper potentiometer has a

a. nonlinear taper.

b. log taper.

c. linear taper.

d. modified log taper.


3-175


A Z taper potentiometer has a

a. log taper.

b. linear taper.

c. modified linear taper.

d. normal taper.


A potentiometer that provides 50% of its resistance at 50% of rotation

a. has a linear taper.

b. has a log taper.

c. is connected as a rheostat.

d. is connected as a 3-terminal pot.


If R2 is adjusted fully CW, R1 (load) will dissipate a maximum of

a. 110 mW.

b. 113 mW.

c. 225 mW.

d. 252 mW.


In this circuit, the maximum voltage at the output (terminal 3) is

a. 17V.

b. 17.5V.

c. 21.5V.

d. 22.27V.


Refer to the graph. If a potentiometer has a Z taper and a 10V input, the output voltage at 50%

rotation is

a. approximately 1.0V.

b. more than 10V.

c. approximately 5V.

d. not on the graph.


3-176

TROUBLESHOOTING


Measure the voltage swing of R2A in your circuit.

R2A = < 0.5 Vdc (R2A set at its minimum CCW position)

R2A maximum (fully CW) = Vdc



Min/Max Value: (10.34) to (11.66)






5. The faulty component in the LINEAR/NONLINEAR VARIABLE RESISTOR circuit block

is





CMS AVAILABLE

None

FAULTS AVAILABLE

Fault 3

DC Fundamentals Unit 12 – Voltage and Current Divider Circuits

3-177

UNIT 12 – VOLTAGE AND CURRENT DIVIDER CIRCUITS

UNIT OBJECTIVE

Demonstrate voltage distribution, current distribution, and the effect of a load on a voltage

divider by using voltage and current divider circuits.

UNIT FUNDAMENTALS


Which statement describes the relationship between voltage and current in the divider circuit?

a. Adding a load increases total current, reduces total resistance, and reduces available voltage.

b. Total current divides between R2 and RLOAD. Load voltage equals VA - VR1.


CMS AVAILABLE

None

FAULTS AVAILABLE

None

NEW TERMS AND WORDS

voltage divider – A string of resistors designed to produce various voltages less than the source

voltage.

current divider – A bank of resistors designed to provide various currents less than the main-

line current.

bank – A parallel circuit with two or more branch circuits.

EQUIPMENT REQUIRED



Multimeter


3-178

Exercise 1 – Voltage Dividers

EXERCISE OBJECTIVE

Demonstrate voltage distribution by using a voltage divider circuit. Verify results with a

multimeter.

EXERCISE DISCUSSION


In this circuit, what is the relationship between the output of the voltage divider (VD) and the

load (RL)?

a. VD increases when the switch is closed.

b. VD is not affected by the position of the switch.

c. VD decreases when the switch is closed.

EXERCISE PROCEDURE


IT = mA

Recall Label for this Question: ITR1NL


Min/Max Value: (4.904) to (7.056)






VR2 = Vdc

Recall Label for this Question: VR2NL


Min/Max Value: (7.831) to (11.27)






3-179


5. CM 8 is activated (R1 is made about equal to R2). Measure the voltage drop across R2.

Compare this voltage to that measured without the CM. Based on your observation, which

statement is correct?

a. The divider output voltage is not affected by a resistor ratio change.

b. The data shows that R1 must equal R2 if the voltage divider is to generate a fixed voltage.

c. The divider output voltage changed because the ratio of R1 to R2 changed.


8. Based on your voltage observations, the greatest change in voltage divider output occurs

when the load resistance

a. is much higher in value than the value of R2.

b. is much lower in value than the value of R2.

c. remains constant.


9. In your circuit, R2 and R3 or R4 form a

a. current divider.

b. voltage divider.

c. voltage-to-current regulator.


10. On your circuit, the divider output voltage changes because R2 and the load (R3 or R4)

share current but

a. have different voltage drops.

b. do not affect the voltage drop of R1.

c. affect the voltage drop of R1.


3-180

REVIEW QUESTIONS


1. An unloaded resistive voltage divider is a

a. series circuit.

b. parallel circuit.

c. series/parallel circuit.

d. combination of series and parallel circuits.


2. The voltage drops in a series voltage divider are

a. inversely proportional to parts of the applied voltage.

b. equal to the current through each resistor divided by the resistance.

c. proportional to the series resistances.

d. proportional to the applied voltage.


3. Refer to the figure. If R2 changed in value to 2600Ω, what would be the voltage drop across

R2?

a. 3.86 Vdc

b. 7.5 Vdc

c. 8.86 Vdc

d. 11.1 Vdc


4. Connect the circuit shown. CM 9 is activated. What is the approximate value of RCM 9?

a. R1 is in parallel with a 1000Ω resistor.

b. R1 is in parallel with a 1800Ω resistor.

c. R1 is in series with a 1000Ω resistor.

d. R2 is in parallel with a 1800Ω resistor.


5. When a load is added to a voltage divider, the resistance of the load is

a. placed in parallel with the voltage divider.

b. combined with the voltage divider.

c. combined with the resistor it parallels.

d. placed in series with the voltage divider.


3-181

CMS AVAILABLE

CM 8

CM 9

FAULTS AVAILABLE

None


3-182

Exercise 2 – Current Dividers

EXERCISE OBJECTIVE

Demonstrate current distribution by using a current divider. Verify results with a multimeter.

EXERCISE DISCUSSION


In the circuit, total current is

a. 50 mA.

b. 15 mA.

c. 5 mA.

EXERCISE PROCEDURE


3. Based on the resistive values of your circuit, what is the relationship between IR2 and IR4?

a. IR2 < IR4

b. IR2 = IR4

c. IR2 > IR4


4. Based on the configuration of your circuit, which statement is correct?

a. R1 and R2 R4 form a voltage divider. R2 and R4 form a current divider.

b. The current through R4 and R2 equals VD/R4 and VD/R2.



IT = mA

Recall Label for this Question: ITCM10R4

Nominal Answer: 7.8

Min/Max Value: (6.396) to (9.204)






3-183


IR2 = mA

Recall Label for this Question: IR2CM10R


Min/Max Value: (4.191) to (5.67 )






IR4 = mA

Recall Label for this Question: IR4CM10R


Min/Max Value: ( .419) to ( .567)






IRCM = mA

Recall Label for this Question: IRCM10R4


Min/Max Value: (2.023) to (2.737)






7. Based on your data, does the sum of the branch currents of your circuit approximately equal

the total circuit current?

a. Yes. The sum of the current divider current must equal total circuit current.

b. No. The total circuit current and branch currents are not equal.

c. The currents are equal only with an applied voltage of 15 Vdc.


3-184


8. Are the branch currents in your circuit directly or inversely related to branch resistances?

a. directly and inversely related

b. directly related

c. inversely related

REVIEW QUESTIONS


1. A current divider requires

a. two or more resistors in series.

b. two or more resistors in parallel.

c. a 10:1 voltage ratio.

d. a 10:1 current ratio.


2. To determine a branch current in a circuit with two parallel resistors, which formula would

you use?

a. IR1 = (IT x R2)/(R1 + R2)

b. IR1 = (R1/R1) + (R2 x IT)

c. IR1 = (R2/R1) + (R2 x VT)

d. IR1 = R1/(RT x VE)


3. Refer to the figure. With switch S1 in position A, the branch current for R2 is

a. 0.57A.

b. 0.057A.

c. 5.7 mA.

d. 577 mA.


4. Refer to the figure above. With switch S1 in the B position, the current through R3 is

a. 14.2 mA.

b. 13.1 mA.

c. 1.25 mA.

d. 0.598 mA.


3-185


5. Connect the circuit shown. Please activate CM 8. IT decreased because R1

a. shorted.

b. stayed the same.

c. decreased in value.

d. increased in value.

CMS AVAILABLE

CM 10

FAULTS AVAILABLE

None


3-186

Exercise 3 – Loading Voltage/Current Dividers

EXERCISE OBJECTIVE

Determine the effects a load has on a voltage divider. Verify results by loading a divider circuit.

EXERCISE DISCUSSION

No Questions

EXERCISE PROCEDURE


3. Connect load resistor R3 to the circuit. Note the voltage reading. Based on your observation,

the divider voltage drops because the load resistor

a. is much lower in value than R2.

b. decreases the total circuit current.

c. decreases the current through R2.


4. Place switch S1 in position A. Notice the change in load resistance. Based on your circuit

voltage reading, the change in voltage between no load (R2 in circuit) and full load (R4 added

by S1) is small because the value of R4 causes

a. little total current change.

b. only a small change in the voltage drop of R1.



6. The load voltage reading (CM activated)

a. is incorrect because total bank current is greater than the current through R1.

b. indicates that total bank resistance is about the same as the value of R1.

c. indicates that zero current flows through R2.


7. Based on the load voltage data, IT is

a. maximum when VR1 is maximum and results in the lowest load voltage.

b. minimum when VR1 is minimum and results in the highest load voltage.



3-187

REVIEW QUESTIONS


1. When a series voltage divider is loaded with a parallel resistor, the divider voltage decreases

because

a. total circuit current decreases.

b. total circuit current increases.

c. total circuit resistance increases.

d. branch current decreases.


2. Voltage dividers are used in electronic equipment to

a. provide circuits with different voltages.

b. load down the power supply.

c. increase the cost of the equipment.

d. increase the voltage of the power supply.


3. Connect the circuit shown. CM10 is activated. Based on the information provided, a resistor

is added

a. in parallel with R1.

b. in series with R1.

c. in series with R2.

d. in parallel with R2.


4. Connect the circuit shown. CM10 is activated and places a 3.3K resistor in parallel with R2.

Based on the information provided, the voltage across R2 is

a. 6.86 Vdc.

b. 7.5 Vdc.

c. 8.08 Vdc.

d. 8.98 Vdc.


5. Refer to the figure. As the load across R2 increases, the voltage drop across R1

a. decreases.

b. increases.

c. stays the same.

d. cannot be determined.


3-188

CMS AVAILABLE

CM 11

CM 10

FAULTS AVAILABLE

None


3-189

UNIT TEST



A voltage divider

a. is a circuit designed to load down a power supply.

b. can provide a number of voltages from a power supply.

c. is very expensive to design and manufacture.

d. increases the power supply output voltage.


The voltage available from a voltage divider is

a. not affected by the resistance of the load.

b. equal to the power supply output voltage.

c. less than the power supply output voltage.

d. greater than the power supply output voltage.


Refer to the figure above. VR2 is

a. 6.6 Vdc.

b. 8.2 Vdc.

c. 13.3 Vdc.

d. 19.9 Vdc.


Current in a parallel bank

a. is proportional to branch resistance.

b. increases when a branch resistance increases.

c. decreases when a branch resistance decreases.

d. is inversely proportional to branch resistance.


The largest value of branch resistor in a parallel bank

a. has the largest current flow.

b. has the smallest current flow.

c. has the largest voltage drop.

d. is the same as the smallest because RE is the same for all resistors in the bank.


3-190


Refer to the figure. With 80 mA of total current, what is the current flow in R2?

a. 60 mA

b. 50 mA

c. 30 mA

d. 20 mA


When you use the proportional voltage method to determine voltage drop, the

a. total current does not have to be known.

b. total current must be known.

c. resistance is divided by the total voltage.

d. formula (VA x RT)/(Rn + RT) is used.


When a load is applied to a voltage divider, its output voltage

a. increases due to the addition of RLOAD.

b. decreases due to the addition of RLOAD.

c. remains the same if the loading ratio is 10:1.

d. increases or decreases depending on the loading ratio.


Refer to the figure above. The voltage available at RLOAD is

a. 6.71 Vdc.

b. 13.4 Vdc.

c. 18.29 Vdc.

d. 22.36 Vdc.


Refer to the figure above. If R2 increased in value to 15 kW,

a. IRLOAD would be 1.6 mA.

b. VRLOAD would be 10 Vdc.

c. IRLOAD would be 16 mA.

d. VRLOAD would not change.


3-191

TROUBLESHOOTING



VR2 = Vdc



Min/Max Value: (8.584) to (9.876)






5. The faulty component in the VOLTAGE DIVIDER circuit block is







VR2 = Vdc



Min/Max Value: (8.584) to (9.876)






5. The faulty component in the VOLTAGE DIVIDER circuit block is






3-192

CMS AVAILABLE

None

FAULTS AVAILABLE

Fault 6

Fault 7

DC Fundamentals Unit 13 – Direct Current Meters

3-193

UNIT 13 – DIRECT CURRENT METERS

UNIT OBJECTIVE

Determine how a meter movement can be used as an ammeter, an ohmmeter, or a voltmeter.

UNIT FUNDAMENTALS

No Questions

CMS AVAILABLE

None

FAULTS AVAILABLE

None

NEW TERMS AND WORDS

moving coil – The part of a meter having a pointer that deflects with current.

permanent magnet – A magnet that retains its magnetism after the magnetizing force has been

removed.

full-scale meter current (IM) – Specified current required for full-scale deflection.

meter resistance (RM) – The ohmic resistance of the wire making up the moving coil.

sensitivity – The ratio of the total resistance of an instrument to the full-scale meter deflection.

EQUIPMENT REQUIRED

F.A.C.E.T. base unit DC FUNDAMENTALS circuit board

Multimeter

DC Milliammeter Module


3-194

Exercise 1 – The DC Ammeter

EXERCISE OBJECTIVE

Determine current by using a basic meter movement. Verify ammeter operation by measuring

known values of current.

EXERCISE DISCUSSION


In the circuit shown, how much current must flow through RSHUNT for a full-scale meter

indication?

a. 10 mA

b. 9 mA

c. 1 mA

EXERCISE PROCEDURE


3. With a full-scale meter movement voltage drop (VM of 2.3) Vdc, what are the values of RM

and IM that you will use in this procedure?

a. RM = 2300Ω, IM = 1 mA full scale

b. RM = 2300Ω, IM = 10 mA full scale

c. RM = 230Ω, IM = 1 mA full scale


4. In the 1-mA circuit with VA at 10 Vdc, what is the required value of R4 for full-scale meter

deflection? Use R4 = (VA – VM)/IM

a. 77Ω

b. 770Ω

c. 7700Ω


3-195


5. What is the purpose of R4?

a. R4 drops the voltage difference between the source and meter voltages.

b. R4 shunts excess current away from the meter coil.

c. R4 increases the power dissipation of the meter coil.


7. What current value is displayed on the meter and what is the circuit current?

a. 10 mA and 10 mA

b. 1 mA and 1 mA

c. 10 mA and 1 mA


9. Slowly adjust R8 until the meter gives a full-scale indication. What current reading is now

indicated by the meter (remember the circuit shunt path)? What is the actual current through the

meter?

a. 10 mA and 1 mA

b. 5 mA and 5 mA

c. 1 mA and 10 mA


10. Based on your circuit observations, what is the purpose of R8?

a. R8 shunts current exceeding 1 mA away from the meter coil.

b. R8 extends the meter scale to indicate a full-scale current of 10 mA.



3-196

REVIEW QUESTIONS


1. The dc resistance of a meter's moving coil

a. has no effect on a circuit.

b. protects the coil from overload.

c. develops a voltage drop.

d. is about zero ohms.


2. The addition of a shunt resistor

a. extends the full-scale indication of the meter.

b. allows the meter coil to pass more current.

c. has no effect on the full-scale indication of the meter.

d. reduces the full-scale indication of the meter.


3. If a dc milliammeter is rated at 10 mA full scale, then

a. the meter can indicate only a 10 mA current.

b. the meter pointer will be at full scale at 10 mA.

c. a shunt is needed to divert 9 mA of current.

d. any current below 10 mA will indicate full scale.


4. To extend the range of the meter used in this exercise to 0–100 mA, make the value of the

shunt resistor that is required for full-scale deflection (100 mA)

a. 0.232Ω.

b. 23.2Ω.

c. 232Ω.

d. 2320Ω.


5. The meter used in this exercise has a permanent magnet and a moving coil, and it is used as a

dc milliammeter. Based on this description,

a. the meter can be directly used for dc and ac current measurements.

b. polarity is not a consideration for connection.

c. the meter can be used only to measure current.

d. the meter must be connected for proper meter movement deflection.


3-197

CMS AVAILABLE

None

FAULTS AVAILABLE

None


3-198

Exercise 2 – The DC Ohmmeter

EXERCISE OBJECTIVE

Measure resistance by using a basic meter movement. Verify ohmmeter operation by measuring

known resistor values.

EXERCISE DISCUSSION


In the circuit, the meter current and pointer deflection are

a. 1 mA and full- scale deflection.

b. 0.5 mA and half- scale deflection.

c. zero current and no deflection.

EXERCISE PROCEDURE


4. Why is the ohmmeter (meter movement) not reading zero ohms?

a. R8 is a maximum resistance and less than 1 mA flows through the circuit.

b. R8 must be adjusted for a full-scale meter deflection (1 mA), which indicates zero ohms

(zero adjust connection).



7. Based on your meter indication, the resistance of R6 is about

a. 49.9 kΩ.

b. 10 kΩ.

c. 1 kΩ.


9. Based on your meter indication, the resistance of R7 is about

a. 49.9 kΩ.

b. 10 kΩ.

c. 1 kΩ.


3-199

REVIEW QUESTIONS


1. An ohms adjust rheostat is usually a part of the internal resistance of an ohmmeter to

compensate for

a. large variations in meter movement resistance.

b. ohms scale errors during manufacture.

c. variations in ohmmeter supply voltage.

d. current variations when small values of resistors are measured.


2. What is the current flow through a series ohmmeter when it indicates zero resistance?

a. maximum

b. minimum

c. halfway between minimum and maximum



3. The total internal resistance of an ohmmeter having a 1.5V internal battery and using a 0-1

mA meter movement would be

a. 3000Ω.

b. 2500Ω.

c. 2300Ω.

d. 1500Ω.


4. If you used the ohmmeter from question 3 and an unknown resistor caused the pointer to go

to half-scale, the value of the unknown resistor would be

a. 2500Ω.

b. 2300Ω.

c. 1500 Ω.

d. 500Ω.


5. When using an ohmmeter, you should disconnect the applied voltage from the circuit being

checked because

a. the voltage source will increase the resistance.

b. the current will decrease the resistance.

c. the ohmmeter has its own internal battery.

d. no current is needed for the meter movement.


3-200

CMS AVAILABLE

None

FAULTS AVAILABLE

None


3-201

Exercise 3 – The DC Voltmeter

EXERCISE OBJECTIVE

Measure volts by using a basic meter movement. Verify voltmeter operation by measuring

known values of voltage.

EXERCISE DISCUSSION

No Questions

EXERCISE PROCEDURE


5. What is the full-scale voltage range of the meter?

a. 100 volts

b. 10 volts

c. 1 volt


6. Monitor the positive variable supply with an external multimeter. Slowly adjust the positive

supply between zero and 10 Vdc. Does your F.A.C.E.T. meter agree with the reading displayed

on your multimeter?

a. Yes. The readings are about the same.

b. No. The readings do not agree.

c. No. The F.A.C.E.T. circuit meter has a milliampere scale.


8. Why does your F.A.C.E.T. meter indicate half-scale (5 Vdc)?

a. The series circuit composed of R8 and R1 drops 5 volts. The remaining 5 volts dropped

across the meter resistance generates a half-scale meter deflection.

b. R8 and R1 shunt 5 volts around the in-circuit meter.

c. The circuit is calibrated for 10 volts full scale. Therefore, a five-volt external voltage

should generate 0.5 mA of circuit current. This 0.5 mA generates a half-scale meter

deflection.


3-202


9. Move the positive lead of the F.A.C.E.T. meter from the R1/R8 circuit to the R2/R8 circuit.

Adjust R8 for a full-scale meter indication. What is the full-scale voltage reading, and what is the

meter current at this reading?

a. 10V indicated at a current of 1 mA

b. 5V indicated at a current of 1 mA

c. 5V indicated at a current of 0.5 mA


10. Moving the F.A.C.E.T. meter from the R1/R8 circuit to the R2/R8 circuit

a. changed the meter calibration to about 5 Vdc full scale at 1 mA of full-scale current.

b. changed the meter full-scale current from 1 mA to 0.5 mA.

c. had no effect on the meter's full-scale voltage indication.

REVIEW QUESTIONS


1. The dc resistance of a meter's moving coil

a. has no effect in a voltmeter current.

b. must be considered as part of the meter multiplier resistance.

c. is connected in parallel with the voltmeter.

d. is used as a meter protector.


2. Multiplier resistors are used in a voltmeter to

a. shunt voltage around the meter movement.

b. limit the voltage at the input of the voltmeter.

c. extend the range of the meter.

d. shunt the current from the meter movement.


3. In the figure, R8 is set for 1050Ω. The meter range must be extended from 10V to 100V full-

scale. What is the required (new) R1 value?

a. 99.5 kΩ

b. 99 Ω

c. 96.65 kΩ

d. 96 kΩ


3-203


4. If the meter used in this exercise were set to the 0-5V range, and if a measured voltage

deflected the pointer to 0.7 on the scale, then the measured voltage would be

a. 1.5 volts.

b. 2 volts.

c. 3 volts.

d. 3.5 volts.


5. In the figure, R8 is set for 1050Ω. R2 is 1650Ω. What is the sensitivity (ohms/volt) of the

meter used in the 0-5V range?

a. 1000

b. 1500

c. 2000

d. 2500

CMS AVAILABLE

None

FAULTS AVAILABLE

None


3-204

UNIT TEST



To connect an ammeter in a circuit,

a. open the circuit at one point and insert the ammeter to complete the circuit.

b. attach the test leads across the component to be measured.

c. remove the power from the circuit.

d. attach the test leads across the voltage source.


A milliammeter shunt

a. decreases the range.

b. is connected in series with the meter.

c. increases the range.

d. converts the meter to a voltmeter.


A 0-1 mA meter with an internal resistance of 1000Ω is converted to a 0-10 mA meter. What is

the value of shunt resistance needed for full-scale deflection at 10 mA?

a. 144.4Ω

b. 111.1Ω

c. 0.144Ω

d. 0.111Ω


An ohmmeter is connected in

a. series with the component being measured.

b. parallel with the voltage source.

c. series/parallel to a circuit.

d. parallel with the component being measured.


What is the current flowing in an ohmmeter when it indicates infinite resistance?

a. minimum

b. maximum

c. halfway between minimum and maximum



3-205


The total internal resistance of an ohmmeter having a 5V internal battery and using a 1 mA

meter movement is

a. 2000Ω.

b. 3000Ω.

c. 4000Ω.

d. 5000Ω.


An ohmmeter is adjusted for zero ohms when

a. the test leads are shorted.

b. the test leads are open.

c. a known resistance is measured.

d. circuit power is off.


A multiplier for a voltmeter is

a. a high resistance in parallel with the meter movement.

b. usually less than the meter resistance.

c. a high resistance in series with the meter movement.

d. usually equal to the meter resistance.


A voltmeter uses a 1 mA, 1500Ω meter movement. What total circuit resistance is required for a

20V full-scale indication?

a. 20Ω

b. 200Ω

c. 2 kΩ

d. 20 kΩ


A voltmeter with a 20V full-scale indication at 1 mA has an internal resistance of 1500Ω. What

multiplier resistor value is required for the voltmeter?

a. 20 kΩ

b. 18.5 kΩ

c. 2 kΩ

d. 1.85 kΩ


3-206

DC Fundamentals Appendix A – Pretest and Posttest Questions and Answers

A-1

APPENDIX A – PRETEST AND POSTTEST QUESTIONS AND ANSWERS


Pretest Questions

1. A decrease in the current of a series circuit can be caused by a

a. source voltage increase.


c. resistance voltage drop decrease.

d. resistance increase.


a. greater in the higher valued resistors.

b. the sum of the current in all components.

c. greater in the lower valued resistors.

d. the same in all parts of the circuit.

3. In an electric circuit, voltage is 100V and resistance is 25 kΩ. The current is

a. 40A.

b. 40 mA.

c. 25 mA.

d. 4 mA.

4. If an electric circuit has a current of 15.4 mA and a source voltage of 20V, the total resistance

is

a. 2000 ohms.

b. 1800 ohms.

c. 1500 ohms.

d. 1300 ohms.

5. In an electrical circuit where the voltage and resistance are known, which form of Ohm's law

is used to find the circuit current?

a. I = ER

b. I = IR

c. I = R/E

d. I = E/R

6. In any electrical circuit, voltage and current are

a. directly proportional.

b. always larger than the resistance.

c. measured in the same units.

d. inversely proportional.


A-2

7. When a switch is closed, its resistance is

a. minimum.

b. infinite.

c. zero ohms.

d. maximum.

8. A DPDT switch can control


b. two conductors in two circuits.

c. one conductor in two circuits.


9. Which of the following statements best describes the pole of a switch?

a. A pole is the movable contact of a switch.

b. A pole the fixed contact of a switch.


d. A pole can not be identified if the type of switch is unknown.

10. When two power sources are connected in a series-aiding configuration, the output voltage

equals the

a. supply with the highest voltage.

b. supply with the lowest voltage.

c. difference of the two supplies.

d. sum of the two supplies.


a. increase voltage output.

b. decrease voltage output.

c. decrease current capacity.

d. increase current capacity.

12. The output of a lead-acid cell is approximately

a. 1.25V.

b. 1.45V.

c. 2.1V.

d. 4V.




c. increase current capacity.

d. decrease current capacity.


A-3

14. The property of conductance is the





15. A resistor with a color band of blue, gray, and black has a value of

a. 680 ohms at 1 percent.

b. 68 ohms at 20 percent.

c. 6.8 ohms at 20 percent.

d. 0.68 ohms at 1 percent.

16. The unit of measurement for electron flow is a(n)

a. volt.

b. ohm.

c. siemens.

d. ampere.

17. A term used to describe opposition to current flow is

a. current.

b. power.

c. resistance.

d. voltage.

18. You should not talk to someone who is operating electrical equipment because you

a. could damage the equipment.


c. both could be injured.


19. When two parts of your body touch an energized circuit, the effect you may feel is a(n)

a. electrical short.

b. electrical shock.

c. burning sensation.

d. short circuit.

20. Why should you have permission to use a power tool for the first time?



c. The instructor can give you safety instructions.



A-4

21. By removing a line cord by the plug you ensure



c. that the line cord will be strained.

d. that you may receive an electrical shock.

22. The term milliampere is abbreviated

a. ma.

b. Ma.

c. mA.

d. milliamp.

23. When measuring circuit current, the ammeter is connected

a. so all circuit current flows through the ammeter.

b. to read a portion of the circuit current.

c. across the component being measured.

d. in parallel to the circuit to read all the circuit current.

24. A graphic symbol on a schematic diagram

a. always looks like the component it represents.

b. shows the electrical construction of the component it represents.

c. is a three dimensional drawing of the component it represents.

d. can be a simple drawing of the component it represents.

25. When measuring voltage, a voltmeter

a. is connected in series with the component.

b. is connected with circuit power off.

c. can also measure resistance and current.

d. is connected in parallel with the component.

26. The sum of voltage drops in a series circuit


b. equals the average value of the voltage drops.



27. When the resistance of a series string decreases,

a. total current decreases.

b. individual resistor voltage drops increase.




A-5

28. When resistance is added to a parallel circuit, total current


b. decreases.

c. increases.


29. Branch voltage in a parallel circuit is


b. equal to the sum of each branch voltage.



30. With three 4.5 kΩ resistors and one 1.5 kΩ resistor in parallel, the total resistance is

a. 750 ohms.

b. 75 ohms.

c. 7.5 ohms.

d. 0.75 ohms.

31. In a parallel circuit, total resistance

a. is the sum of the branch resistances.

b. is greater than the resistance of any branch resistor.

c. increases when the circuit current increases.

d. is less than the resistance of any branch.

32. A series-parallel resistive circuit will appear as what kind of load to a power source?

a. multiple

b. branch

c. single

d. double

33. The total current in a series-parallel circuit equals the

a. sum of the parallel branch circuit currents.

b. applied voltage multiplied by the total resistance.

c. total resistance divided by the applied voltage.

d. sum of the branch circuit currents.

34. When three 10 kΩ resistors connect to form a series-parallel circuit, total resistance (RT) is

a. 15 kΩ.

b. 12.5 kΩ.

c. 10 kΩ.

d. 5 kΩ.


A-6

35. The total voltage in a series-parallel circuit is

a. equal to the sum of the voltage drops across each resistor in the circuit.

b. distributed across each branch in the circuit.



36. The basic unit of electric power is the

a. ampere.

b. volt.

c. ohm.

d. watt.

37. A 5Ω resistor connected to a 20 Vdc source dissipates

a. 4 watts.

b. 5 watts.

c. 80 watts.

d. 100 watts.

38. Total power in a series circuit equals the


b. circuit voltage divided by the circuit current.

c. difference of the power dissipated by each resistor.

d. sum of the power dissipated by each resistor.

39. A rheostat in an electrical circuit



c. is connected in series with the load.

d. controls the source voltage.

40. The taper of a potentiometer is the


b. relationship between resistance and shaft rotation.

c. degree of shaft rotation.

d. ratio of output voltage to the input voltage.

41. A potentiometer that provides 50 percent of its resistance at 50 degress of rotation

a. has a log taper.

b. is connected to a rheostat.

c. has a linear taper.

d. is connected as a three-terminal pot.


A-7

42. A potentiometer that provides 10 percent of its resistance at 50 degrees of rotation

a. is connected as a rheostat.

b. has a linear taper.

c. is connected as a three-terminal pot.

d. has a log taper.

43. A voltage divider

a. is a circuit designed to load down the power supply.

b. is very expensive to design and manufacture.

c. provides a number of voltages from the power supply.


44. When a voltage divider has a load applied, the loaded voltage

a. increases due to the addition of RL.

b. remains the same.

c. increases depending upon the loading ratio.

d. decreases due to the addition of RL.

45. The distribution of current in a voltage divider is accomplished by


b. a series voltage divider.

c. parallel voltage dividers.

d. series current dividers.

46. When you troubleshoot an electrical circuit, the first and least troublesome step to perform is

a

a. complete and detailed circuit calibration.

b. 4-hour burn-in to ensure that a defective component fails.

c. diagnostic performance check.

d. thorough visual inspection.

47. A milliampere shunt





48. The current flowing in an ohmmeter that indicates infinite resistance is

a. minimum.

b. maximum.

c. halfway between minimum and maximum.



A-8

49. A 1 mA meter movement used in an ohmmeter with a 5V internal battery has an internal

resistance of

a. 5 kΩ.

b. 4 kΩ.

c. 3 kΩ.

d. 2 kΩ.

50. A 1 mA meter with RM equal to 1500 ohms and a full-scale reading of 20 volts has a total

internal resistance of

a. 30 kΩ.

b. 20 kΩ.

c. 10 kΩ.

d. 5 kΩ.


A-9

Posttest Questions


1. In an electric circuit, voltage is 100V and resistance is 25 kΩ. The current is

a. 40A.

b. 40 mA.

c. 25 mA.

d. 4 mA.

2. When a switch is closed, its resistance is

a. minimum.

b. infinite.

c. zero ohms.

d. maximum.

3. When two power sources are connected in a series-aiding configuration, the output voltage

equals the

a. supply with the highest voltage.

b. supply with the lowest voltage.

c. difference of the two supplies.

d. sum of the two supplies.

4. The property of conductance is the





5. By removing a line cord by the plug you ensure



c. that the line cord will be strained.

d. that you may receive an electrical shock.

6. The sum of voltage drops in a series circuit


b. equals the average value of the voltage drops.




A-10

7. A decrease in the current of a series circuit can be caused by a

a. source voltage increase.


c. resistance voltage drop decrease.

d. resistance increase.

8. Which of the following statements best describes the pole of a switch?

a. A pole is the movable contact of a switch.

b. A pole the fixed contact of a switch.


d. A pole can not be identified if the type of switch is unknown.

9. The unit of measurement for electron flow is a(n)

a. volt.

b. ohm.

c. siemens.

d. ampere.

10. When measuring circuit current, the ammeter is connected

a. so all circuit current flows through the ammeter.

b. to read a portion of the circuit current.

c. across the component being measured.

d. in parallel to the circuit to read all the circuit current.

11. When resistance is added to a parallel circuit, total current


b. decreases.

c. increases.


12. If an electric circuit has a current of 15.4 mA and a source voltage of 20V, the total resistance

is

a. 2000 ohms.

b. 1800 ohms.

c. 1500 ohms.

d. 1300 ohms.

13. In any electrical circuit, voltage and current are

a. directly proportional.

b. always larger than the resistance.

c. measured in the same units.

d. inversely proportional.


A-11

14. A resistor with a color band of blue, gray, and black has a value of

a. 680 ohms at 1 percent.

b. 68 ohms at 20 percent.

c. 6.8 ohms at 20 percent.

d. 0.68 ohms at 1 percent.

15. You should not talk to someone who is operating electrical equipment because you

a. could damage the equipment.


c. both could be injured.


16. The taper of a potentiometer is the


b. relationship between resistance and shaft rotation.

c. degree of shaft rotation.

d. ratio of output voltage to the input voltage.

17. The distribution of current in a voltage divider is accomplished by


b. a series voltage divider.

c. parallel voltage dividers.

d. series current dividers.

18. A 1 mA meter movement used in an ohmmeter with a 5V internal battery has an internal

resistance of

a. 5 kΩ.

b. 4 kΩ.

c. 3 kΩ.

d. 2 kΩ.

19. In a parallel circuit, total resistance

a. is the sum of the branch resistances.

b. is greater than the resistance of any branch resistor.

c. increases when the circuit current increases.

d. is less than the resistance of any branch.

20. When measuring voltage, a voltmeter

a. is connected in series with the component.

b. is connected with circuit power off.

c. can also measure resistance and current.

d. is connected in parallel with the component.


A-12

21. A term used to describe opposition to current flow is

a. current.

b. power.

c. resistance.

d. voltage.

22. When a voltage divider has a load applied, the loaded voltage

a. increases due to the addition of RL.

b. remains the same.

c. increases depending upon the loading ratio.

d. decreases due to the addition of RL.

23. A rheostat in an electrical circuit



c. is connected in series with the load.

d. controls the source voltage.

24. The total current in a series-parallel circuit equals the

a. sum of the parallel branch circuit currents.

b. applied voltage multiplied by the total resistance.

c. total resistance divided by the applied voltage.

d. sum of the branch circuit currents.

25. When the resistance of a series string decreases,

a. total current decreases.

b. individual resistor voltage drops increase.



26. A graphic symbol on a schematic diagram

a. always looks like the component it represents.

b. shows the electrical construction of the component it represents.

c. is a three dimensional drawing of the component it represents.

d. can be a simple drawing of the component it represents.

27. Branch voltage in a parallel circuit is


b. equal to the sum of each branch voltage.




A-13




c. decrease current capacity.

d. increase current capacity.




c. increase current capacity.

d. decrease current capacity.

30. The output of a lead-acid cell is approximately

a. 1.25V

b. 1.45V.

c. 2.1V.

d. 4V.

31. When two parts of your body touch an energized circuit, the effect you may feel is a(n)

a. electrical short.

b. electrical shock.

c. burning sensation.

d. short circuit.

32. With three 4.5 kΩ resistors and one 1.5 kΩ resistor in parallel, the total resistance is

a. 750 ohms.

b. 75 ohms.

c. 7.5 ohms.

d. 0.75 ohms.

33. The term milliampere is abbreviated

a. ma.

b. Ma.

c. mA.

d. milliamp.

34. A DPDT switch can control


b. two conductors in two circuits.

c. one conductor in two circuits.



A-14

35. Why should you have permission to use a power tool for the first time?



c. The instructor can give you safety instructions.


36. When three 10 kΩ resistors connect to form a series-parallel circuit, total resistance (RT) is

a. 15 kΩ.

b. 12.5 kΩ.

c. 10 kΩ.

d. 5 kΩ.

37. In an electrical circuit where the voltage and resistance are known, which form of Ohm's law

is used to find the circuit current?

a. I = ER

b. I = IR

c. I = R/E

d. I = E/R


a. greater in the higher valued resistors.

b. the sum of the current in all components.

c. greater in the lower valued resistors.

d. the same in all parts of the circuit.

39. The total voltage in a series-parallel circuit is

a. equal to the sum of the voltage drops across each resistor in the circuit.

b. distributed across each branch in the circuit.



40. Total power in a series circuit equals the


b. circuit voltage divided by the circuit current.

c. difference of the power dissipated by each resistor.

d. sum of the power dissipated by each resistor.

41. A potentiometer that provides 50 percent of its resistance at 50 degress of rotation

a. has a log taper.





A-15

42. A series-parallel resistive circuit will appear as what kind of load to a power source?

a. multiple

b. branch

c. single

d. double

43. A milliampere shunt





44. A voltage divider

a. is a circuit designed to load down the power supply.

b. is very expensive to design and manufacture.

c. provides a number of voltages from the power supply.


45. The current flowing in an ohmmeter that indicates infinite resistance is

a. minimum.

b. maximum.

c. halfway between minimum and maximum.


46. The basic unit of electric power is the

a. ampere.

b. volt.

c. ohm.

d. watt.

47. A potentiometer that provides 50 percent of its resistance at 50 degrees of rotation

a. has a log taper.




48. A 5Ω resistor connected to a 20 Vdc source dissipates

a. 4 watts.

b. 5 watts.

c. 80 watts.

d. 100 watts.


A-16

49. When you troubleshoot an electrical circuit, the first and least troublesome step to perform is

a

a. complete and detailed circuit calibration.

b. 4-hour burn-in to ensure that a defective component fails.

c. diagnostic performance check.

d. thorough visual inspection.

50. A 1 mA meter with RM equal to 1500 ohms and a full-scale reading of 20 volts has a total

internal resistance of

a. 30 kΩ.

b. 20 kΩ.

c. 10 kΩ.

d. 5 kΩ.

DC Fundamentals Appendix B – Faults and Circuit Modifications (CMs)

B-1

APPENDIX B – FAULTS AND CIRCUIT MODIFICATIONS (CMS)

CM SCHEMATIC

SWITCH NO.

FAULT ACTION

– 21 1 opens R1

– 22 2 shorts R2

– 23 3 opens R2

– 24 4 R2 = 3110Ω

– 25 5 R3 = 6900Ω

– 26 6 places 910Ω in parallel with

910-Ω R1

– 27 7 places 2.7 kΩ in parallel

with 1.6-kΩ R2

– 28 8 places 6.2 kΩ in parallel

with 1.2-kΩ R2

– 29 9 R1 = 800Ω

– 30 10 R1 = 1470Ω

– 31 11 places 220 in parallel with

2-kΩ R3

– 32 12 shorts R2

1 1 – R1 = 2 kΩ

2 2 – R3 = 1240Ω

3 3 – places 2.4 kΩ in parallel

with 2.5-kΩ R2A or R2B


with 47-kΩ R3


with 10-kΩ R1

6 6 – R2 = 2630Ω

7 7 – R3 = 5030Ω

8 8 – R1 = 1590Ω


with 910-Ω R1


with 1.6-kΩ R2

11 11 – R4 = 1600Ω


with 1.2-kΩ R2

13 13 – R1 = 1330Ω

14 14 – R3 = 7100Ω

15 15 – shorts R3

16 16 – places 1 kΩ resistor

between "A" and common

DC Fundamentals Appendix B – Faults and Circuit Modifications (CMs)

B-2

CM SCHEMATIC

SWITCH NO.

FAULT ACTION

17 17 – R1 = 1240Ω

18 18 – R4 = 1470Ω

19 19 – R2 = 3200Ω

20 20 – places 470Ω in parallel with

510-Ω R1

DC Fundamentals Appendix C – Board and Courseware Troubleshooting

C-1

APPENDIX C – BOARD AND COURSEWARE TROUBLESHOOTING

Circuit Board Problems

The F.A.C.E.T. equipment is carefully designed, manufactured, and tested to assure long,

reliable life. If you suspect a genuine failure in the equipment, the following steps should be

followed to trace a problem.

A. ALWAYS insert the board into a base unit before attempting to use an ohmmeter for

troubleshooting. The schematic diagrams imprinted on the boards are modified by the

absence of base unit switch connections; therefore, ohmmeter checks will produce erroneous

results with disconnected boards. Do not apply power to the base unit when you perform

resistance checks.

B. Information describing fault switch functions is provided in Appendix B in this instructor

guide.

Courseware Problems

The F.A.C.E.T. courseware has been written to meet carefully selected objectives. All exercises

have been tested for accuracy, and information presented in discussions has been reviewed for

technical content. Tolerances have been computed for all procedure and review question answers

to assure that responses are not invalidated by component or instrument errors.

Nevertheless, you or your students may discover mistakes or experience difficulty in using our

publications. We appreciate your comments and assure you that we will weigh them carefully in

our ongoing product improvement efforts.

As we address courseware problems, we will post corrections for download from our web site,

www.labvolt.com. Select the customer support tab, and then choose product line: F.A.C.E.T..

Select a course, select from a list of symptoms that have been addressed, and follow the

instructions.

DC Fundamentals Appendix C – Board and Courseware Troubleshooting

C-2

We will do our best to help you resolve problems if you call the number below. However, for

best results, and to avoid confusion, we prefer that you write with a description of the problem.

If you write, please include the following information:

• Your name, title, mailing address, and telephone number (please include the best time to

reach you).

• Publication title and number.

• Page number(s), and step and/or figure number(s) of affected material.

• Complete description of the problem encountered and any additional information that may

help us solve the problem.

Send your courseware comments to:

[email protected]

Lab-Volt Systems

P.O. Box 686

Farmingdale, NJ 07727

ATTN: Technical Support

If you prefer to telephone regarding hardware or courseware problems, call us between 9:00 AM

and 4:30 PM (Eastern time) at: (800) 522-4436 or (888)-LAB-VOLT.

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