Download Ohm`s Law - Schuylkill Technology Center

RESIDENTIAL & INDUSTRIAL
ELECTRICITY

NAME:
DATE:
DATE DUE:


Schuylkill Technology
CenterSouth Campus
15 Maple Avenue
Marlin, Pennsylvania 17951
(570) 544-4748
COURSE TITLE:
Fundamentals of Basic Electricity
DUTY TITLE :
Construction Math
DUTY NUMBER:
200
TASK #1:
Understanding Ohm’s Law
PURPOSE:
To understand and be able to apply the OHM’S Law values
in residential circuitry.
PROGRAM OF STUDY #:
201
202
203
204
205
206
207
Problem solve using whole numbers.
Problem solve using fractions.
Problem solve using decimal numbers.
Convert decimals, fractions and percents.
Problem solve using the metric system.
Calculate basic construction problems using geometry formulas.
Calculate basic construction problems using algebraic formulas.
REVISION: 2016
1
*CORE CURRICULUM STANDARDS*
ENGLISH LANGUAGE ARTS
CC.1.3.11-12.I Determine or clarify the meaning of unknown and multiple-meaning words and phrases based on grade level reading and content,
choosing flexibly from a range of strategies and tools.
CC.1.4.11-12.A Write informative/ explanatory texts to examine and convey complex ideas, concepts, and information clearly and accurately.
MATH
CC.2.1.HS.F.4 Use units as a way to understand problems and to guide the solution of multi-step problems.
CC.2.1.HS.F.6 Extend the knowledge of arithmetic operations and apply to complex numbers.
READING IN SCIENCE & TECHNOLOGY
CC.3.5.11-12.D. Determine the meaning of symbols, key terms, and other domain-specific words and phrases as they are used in a specific scientific
or technical context relevant to grades 11–12 texts and topics.
WRITING IN SCIENCE & TECHNOLOGY
CC.3.6.11-12.H. Draw evidence from informational texts to support analysis, reflection, and research.
2
*ACADEMIC STANDARDS*
*ACADEMIC STANDARDS *
READING, WRITING, SPEAKING & LISTENING
1.1.11.A Locate various texts, assigned for independent projects before reading.
1.1.11.D Identify strategies that were most effective in learning
1.1.11.E Establish a reading vocabulary by using new words
1.1.11.F Understanding the meaning of, and apply key vocabulary across the various subject areas
1.4.11.D Maintain a written record of activities
1.6.11.A Listen to others, ask questions, and take notes
MATH
2.2.11.A Develop and use computation concepts
2.2.11.B Use estimation for problems that don’t need exact answers
2.2.11.C Constructing and applying mathematical models
2.2.11.D Describe and explain errors that may occur in estimates
2.2.11.E Recognize that the degree of precision need in calculating
2.3.11.A Selecting and using the right units and tools to measure precise measurements
2.5.11.A Using appropriate mathematical concepts for multi-step problems
2.5.11.B Use symbols, terminology, mathematical rules, Etc.
2.5.11.C Presenting mathematical procedures and results
SCIENCE
3.1.12.A Apply concepts of systems, subsystems feedback and control to solve complex technological problems
3.1.12.B Apply concepts of models as a method predict and understand science and technology
3.1.12.C Assess and apply patterns in science and technology
3.1.12D Analyze scale as a way of relating concepts and ideas to one another by some measure
3.1.12.E Evaluate change in nature, physical systems and man made systems
3.2.12.A Evaluate the nature of scientific and technological knowledge
3.2.12.B Evaluate experimental information for appropriateness
3.2.12.C Apply elements of scientific inquiry to solve multi – step problems
3.2.12.D Analyze the technological design process to solve problems
3.4.12.A Apply concepts about the structure and properties of matter
3.4.12.B Apply energy sources and conversions and their relationship to heat and temperature
3.4.12.C Apply the principles of motion and force
3.8.12.A Synthesize the interactions and constraints of science
3.8.12.B Use of ingenuity and technological resources to solve specific societal needs and improve the quality of life
3.8.12.C Evaluate the consequences and impacts of scientific and technological solutions
ECOLOGY STANDARDS
4.2.10.A Explain that renewable and non renewable resources supply energy and material.
4.2.10.B Evaluate factors affecting availability of natural resources.
4.2.10.C Analyze the use of renewable and non renewable resources.
4.2.12.B Analyze factors affecting the availability of renewable and non renewable resources.
4.3.10.A Describe environmental health issues.
4.3.10.B Explain how multiple variables determine the effects of pollution on environmental health, natural processes and human practices.
4.3.12.C Analyze the need for a healthy environment.
4.8.12.A Explain how technology has influenced the sustainability of natural resources over time.
CAREER & EDUCATION
13.1.11.A Relate careers to individual interest, abilities, and aptitudes
13.2.11.E Demonstrate in the career acquisition process the essential knowledge needed
13.3.11.A Evaluate personal attitudes that support career advancement
ASSESSMENT ANCHORS
M11.A.3.1.1 Simplify expressions using the order of operations
M11.A.2.1.3 Use proportional relationships in problem solving settings
M11.A.1.2 Apply any number theory concepts to show relationships between real numbers in problem solving
3
STUDENT
The student will understand all the values presented in the OHM’S Law formula.
TERMINAL PERFORMANCE OBJECTIVE
Given all related information the student will be able to identify all components of
OHM’S Law to 100% accuracy.
SAFETY


Always wear safety glasses while in the shop area.
Review and Discuss MAVCC “Blood Borne Pathogens” Video
EQUIPMENT & SUPPLIES
1. Obtain OHM’S Law formula sheet from the instructor.
2. K-W-L Work Sheet
VOCABULARY
CC.1.3.11-12.I=Determine or clarify the meaning of unknown and multiple-meaning words and phrases
based on grade level reading and content, choosing flexibly from a range of strategies and tools.
1.1.11.F=Understanding the meaning of, and apply key vocabulary across the various subject areas
1. E
2. I
3. R
4. P
5. ELECTRON
6. PROTON
7. NEUTRON
8. CHARGE
9. NEUCLEUS
10. POSITIVE ATOM
11. SPARK
12. NEGATIVE GHARGE
13. POSITIVE CHARGE
14. STATIC ELECTRICITY
4
CC.1.3.11-12.I Determine or clarify the meaning of unknown and multiple-meaning words and
phrases based on grade level reading and content, choosing flexibly from a range of strategies and
tools.
Residential & Industrial Electricity
Pre/Post Learning Concept Check
Name:
Date:
Level:
Lesson Objective:
+/-
Key Vocabulary Terms
PRE
+/POST
Ohm
Series
Parallel
Volt
Current
Tension
Proton
Neutron
Lesson Conclusion:
MAX Teaching
2016
5
PROCEDURE
1) Attend lecture by instructor.
2) Review chapter in text books.
3) Complete K-W-L Literacy Assignment by Picking an Article From the
“Electrical Contractor” Magazine Located in the Theory Room. You can pick any
article you feel is important to the electrical trade.
4) Students are to write the definitions for vocabulary terms on the previous page.
5) Students are to write as many related terms for E, I, R, and P on the following lines.
Introduction
CC.1.3.11-12.I=Determine or clarify the meaning of unknown and multiple-meaning words and phrases
based on grade level reading and content, choosing flexibly from a range of strategies and tools.
1.1.11.F=Understanding the meaning of, and apply key vocabulary across the various subject areas
13.1.11.A=Relate careers to individual interest, abilities, and aptitudes
1.6.11.A=Listen to others, ask questions, and take notes
1. Electricity has a standard set of values.
2. To work with electricity one must know the rules and
understand them.
3. Volts, amps, and ohms are the same everywhere.
4. After studying this unit, the student will be able to:
Define a coulomb.
Define an amp.
Define a volt.
Define an ohm.
Define a watt.
5. Compute different electrical values using the Ohm’s law
formulas.
6. Discuss different types of electrical circuits.
7. Select the proper Ohm’s law formula from a chart.
6
Glossary
1.1.11.F=Understanding the meaning of, and apply key vocabulary across the various subject areas
Amp —
British Thermal Unit (BTU) — the amount of heat necessary to
change the temperature of one pound of water one degree
Fahrenheit
Complete path
Conventional current flow theory — an older theory that states
that electric current flows from the more positive source to the
more negative source
Coulomb
Electromotive Force (EMF) —
Electron theory — the theory that states that electricity flows from
the more negative power source to the more positive power source
Grounding conductor
Horsepower — a common measure of power; the base was
established at 550 pound feet per second; in electrical quantities,
746 watts equals one hp
Impedance
Joule — a metric measure of power similar to the English
measure watt
Neutral conductor:
Ohm:
Ohm’s law:
Power:
Resistance:
Volt:
Watt:
7
The Coulomb
 A quantity of measurement for electrons
 Equals 6.25 1018 electrons
 Named for Charles Augustin de Coulomb
 Developed a law dealing with the attraction and repulsion of electrostatic
charges The force of electrostatic attraction or repulsion is directly
proportional to the product of the two charges and inversely proportional to
the square of the distance between them
The Amp
 Named for Andre Ampere known for his work in
electromagnetism
 One amp flows through a wire when one coulomb flows
past a point in one second
 kiloamp = 1000 amps
 milliamps = .001 amps
 microamps = .000001 amps
 The measurement of the amount of electricity flowing
through a circuit
 Also called current
 The symbol for amps is the letter “A”
 The symbol for current is the letter “I”
 Both symbols are used in electrical formulas
Electron Theory
 One of two electron flow theories
 States that since electrons are negative particles, current
flows from the most negative point to the most positive
point in a circuit
 The electron theory is more widely accepted as being
correct
Conventional Current Theory
 Older than the electron theory
 States that current flows from the most positive point to the
most negative point in a circuit
 While the electron theory has almost been proved correct,
the conventional theory is used for several reasons
 Most electronic circuits use the negative terminal for
ground or common
 b. The positive terminal is considered above ground or hot
 c. The arrows on the semiconductor symbols point in the
direction of conventional current flow
 d. The electron theory has the current flowing against the
arrows
8



Most electronic schematics are drawn with the current flow from the more
positive to the more negative
Most positive part of circuit shown at the top and the most negative (ground)
is shown at the bottom
Most people find it easier to work from the top down
The Speed of Current
1. First one must determine what is being measured
2. It is estimated that one electron moves at about 3” per hour at
one amp of current flow
3. Must determine if circuit is AC, DC, or radio wave
4. Radio waves travel at about the speed of light
a. 186,000 miles per second
b. 300,000 meters per second
Basic Electrical Circuits
1. Complete path must exist before current can flow
2. Source, conductors, and load form a closed loop or complete
path
3. The circuit load limits the amount of current that can flow in a
circuit
5. Open circuit exists when something prevents the current from
completing its complete path
a. Loose wire or open switch
6. A short circuit occurs when a hot circuit conductor and a neutral
conductor make contact
b. Also occurs when two hot conductors make contact
c. Because the load (current limiter) is bypassed, excessive
current can flow generally will cause the circuit breaker or
fuse to trip
d. Can damage equipment, melt wiring, cause fires and
serious injury
Grounded circuit
e. Often confused with a short circuit
f. Can also allow excessive current flow
g. Occurs when a path to ground, other than the one intended,
is established
d. Many circuits contain a grounding conductor
7. Typical 120-volt circuit
a. Hot conductor is connected to the fuse or circuit breaker to
provide power
b. Neutral (grounded) conductor completes circuit path by a
return path to the power source
c. Grounding conductor is connected to all metal frames to
provide a
low-resistance path to ground A complete path
includes a return wire (neutral) to complete the path.
9
8. Another name for circuit load is resistance. An example of
a grounded circuit would be a hot wire touching a copper
water pipe. Remember, a 120-volt circuit can be extremely
dangerous because of the amount of current it has and
because people get too comfortable around it.
9. Be sure that all metal boxes and devices are properly
grounded.
10. Grounding conductor is not considered a circuit conductor
a. Only carries current when a fault occurs
b. Used to prevent shock when a hot conductor comes in
contact with a metal frame.
c. No path to ground exists without grounding conductor
anyone who
touches an energized metal frame and a
grounded point completes the circuit and shock occurs
d. Extension cords must be equipped with grounding prongs;
they are never to be removed or bypassed
Volts
1. Known as electromotive force (EMF) or electrical pressure
2. The force that pushes electrons through a conductor
3. Defined as the amount of potential needed to cause one
coulomb to produce one joule of work
4. Volts do not flow; they cause electrons to flow
a. Figure 3-12
b. Water pressure is a good example
5. Volts are thought of as the potential to do something
6. Volts must be present for current to flow
7. The symbol for electromotive force is the letter “E”
8. The symbol for volts is the letter “V”
9. Both are used in electrical formulas
Ohms
1.
2.
3.
4.
5.
A unit of resistance to current flow
Named after Georg S. Ohm
Ohms represented by the Greek letter omega
In electrical formulas, the letter “R” is used
An ohm is defined as the amount of resistance that will allow
one amp to flow through a circuit when one volt is applied
6. Without resistance every circuit is a short circuit
7. All electrical loads are measured in ohms
a. Motors, lamps, heating elements
8. Resistance is used to control the flow of electrons
b. Figure 3-13
9. The higher the resistance, the greater the hindrance to current
flow
10. Whenever there is resistance to current flow, heat is produced
c. Figure 3-14
10
Watts
b)
c)
d)
e)
A measure of the power being used in a circuit
Named after James Watt
Represented by either the letter “W” for watts or the letter “P” for power
Watts are proportional to the amount of current flow and the amount of voltage in
a circuit
f) Electrical energy must be converted into some other form of energy before there
can be power or watts mechanical, etc.
Other Measures of Power
a) Horsepower is the amount of force needed to raise a one-pound weight one foot
a. The average horse can do 550 foot/pounds of work per
second
b. 1 horsepower = 550 ft-lbs/sec
c. 1 horsepower = 33,000 ft-lbs/min
d. 1 horsepower = 746 watts
2. British Thermal Unit (BTU)
a. the amount of heat required to raise the temperature of one
pound of water one degree Fahrenheit
b. Metric equivalent to the BTU
c. Amount of heat required to raise the temperature of one
gram of water one degree Celsius
3. Joule
a. Metric equivalent of the watt
b. Equals one newton per meter or 100,000 dynes (about 3.5
ounces)/meter
c. Equals the amount of work done by one coulomb flowing
through one volt
d. Also equals the amount of work done by one watt for one
second
11
Ohm’s Law
CC.2.1.HS.F.4 =Use units as a way to understand problems and to guide the solution of multi-step
problems.
3.2.12.C=Apply elements of scientific inquiry to solve multi – step problems
M11.A.3.1. =Simplify expressions using the order of operations
a) It takes one volt to push one amp through one ohm
b) All electrical quantities are proportional to one another
c) In DC circuits, current is directly proportional to the voltage and inversely
proportional to the resistance
d) States that voltage equals the amperage times the resistance
a. E = I R
b. I = E/R
c. R = E/I
ii) Adds formulas for watts
Metric Units
a) Metric notation is based on units of 10
b) Electrical field uses Engineering Notation
i) Based on units of 1000 instead of 10

3.2.12.C = Apply elements of scientific inquiry to solve multi – step problems
Summary
a) A coulomb is a quantity of measurement of electrons
b) An amp (A) is one coulomb per second
c) Either the letter “I”, which stands for intensity of current flow, or the letter “A”,
which stands for amps, can be used in Ohm’s law formulas
d) Voltage is referred to as electrical pressure, potential difference, or electromotive
force
a. An “E” or a “V” can be used to represent voltage in Ohm’s
law formulas
e) An ohm is a measurement of resistance in an electrical circuit
i) The letter “R” is used in Ohm’s law formulas
f) The watt is a measurement of power in an electrical circuit
i) The letter “W” (watt) or the letter “P” (power) is used in Ohm’s law formulas
g) Electrical measurements are generally expressed in engineering notation
h) Engineering notation differs from the standard metric system in that it uses steps
of 1000 instead of steps of 10
i) Before current can flow, there must be a complete circuit
j) A short circuit has little or no resistance
12
REFERENCE
PAGES
13
14
“E”

‘ E ‘ IS THE SYMBOL FOR ELECTRICAL PRESSURE.

ELECTRICAL PRESSURE IS RATED IN VOLTAGE.

VOLTAGE IS THE DIFFERENCE BETWEEN UNLIKE CHARGES
OR AN ELECTRICAL IMBALANCE LIKE [ - ] TO [ +] , [ - ] TO
NEUTRAL OR [+ ] TO NEUTRAL.

VOLTAGE DOES NOT TRAVEL THROUGH A CONDUCTOR.

OTHER NAMES GIVEN FOR ELECTRICAL PRESSURE ARE:
1. VOLTAGE
2. TENSION
3. POTENTIAL
4. POTENTIAL DIFFERENCE
5. VOLTS

VOLTAGE DIVIDES IN SERIES.

VOLTAGE IS CONSTANT IN PARALLEL.
15
“I”

‘ I ‘ IS THE SYMBOL FOR ELECTRON FLOW.

ELECTRON FLOW IS RATED IN AMPERAGE.

AMPERAGE IS THE FLOW OF ELECTRONS THROUGH A
CONDUCTOR.

AN AMPERE IS A LARGE AMOUNT OF ELECTRONS
(COLOUMBS) MOVING VERY FAST.

OTHER NAMES GIVEN FOR AMPERAGE ARE :
1. ELECTRON FLOW
2. CURRENT
3. AMPS
4. LOAD

CURRENT IS CONSTANT IN SERIES.

CURRENT ADDS IN PARALLEL.
16
“R”

‘ R ‘ IS THE SYMBOL FOR ELECTRICAL RESISTANCE.

ELECTRICAL RESISTANCE IS RATED IN OHMS.

OHMS IS THE OPPOSITION TO CURRENT FLOW.

OTHER NAMES GIVEN FOR ELECTRICAL RESISTANCE
ARE:
1. OHMS
2. OHMIC VALUE
3. RESISTANCE
4. VALUE

RESISTANCE ADDS IN SERIES.

RESISTANCE DIVIDES IN PARALLEL.
17
“P”

‘ P ‘ IS THE SYMBOL FOR ELECTRICAL POWER.

ELECTRICAL POWER IS RATED IN WATTAGE.

WATTAGE IS THE AMOUNT OF ELECTRICAL WORK OR
POWER A DEVICE CAN PRODUCE OR HANDLE.

OTHER NAMES GIVEN FOR WATTAGE ARE:
1. WATTS
2. POWER
3. LOAD
4. KILO VOLT AMPS (K.V.A.)
18
A little bit about the life and times of Georg Simon Ohm:
Georg Simon Ohm was a German physicist born in Erlangen, Bavaria, on March
16, 1787. As a high school teacher, Ohm started his research with the then recently
invented electric cell, invented by Italian Conte Alessandro Volta. Using
equipment of his own creation, Ohm determined that the current that flows through
a wire is proportional to its cross sectional area and inversely proportional to its
length. Using the results of his experiments, Georg Simon Ohm was able to define
the fundamental relationship between voltage, current, and resistance. These
fundamental relationships are of such great importance, that they represent the true
beginning of electrical circuit analysis. Unfortunately, when Ohm published his
finding in 1827, his ideas were dismissed by his colleagues. Ohm was forced to
resign from his high-school teaching position and he lived in poverty and shame.
However, his research efforts gained allot of support outside of Germany. In 1849
Georg Simon Ohm was finally recognized for his efforts by being appointed as a
professor at the University of Munich.
19
20
21
NAME:
LEVEL:
DATE:
CHECK LIST FOR OHM’S LAW
STEPS/TASKS
MEETS
STANDARDS
NEEDS
IMPROVEMENT
1) THE STUDENT ADHERED TO ALL SAFETY
RULES.
2) THE STUDENT IDENTIFIED ALL TERMS FOR
VOLTAGE.
3) THE STUDENT IDENTIFIED ALL TERMS FOR
CURRENT.
4) THE STUDENT IDENTIFIED ALL TERMS FOR
RESISTANCE.
5) THE STUDENT IDENTIFIED ALL TERMS FOR
WATTAGE.
6) THE STUDENT COMPLETED MATHMATICAL
EQUATIONS FOR OHM’S LAW TO 100%
ACCURACY.
7) THE STUDENT COMPLETED ALL VOCABULARY
TO 100% ACCURACY.
8) THE STUDENT COMPLETED ALL WRITTEN
WORK TO 100% ACCURACY.
9) THE STUDENT COMPLETED THE WRITTEN
ASSESSMENT TO 80% ACCURACY.
* ALL STEPS/TASKS MUST MEET THE STANDARDS IN ORDER TO ACHIEVE MASTERY.*
COMMENTS:
INSTRUCTOR SIGNATURE:
DATE:
22
CC.3.6.11-12.E. Use technology, including the Internet, to produce, publish, and update individual or shared writing
products in response to ongoing feedback, including new arguments or information.
CC.3.6.11-12.H. Draw evidence from informational texts to support analysis, reflection, and research.
Residential & Industrial Electricity
K-W-L WORKSHEET
NAME:
LEVEL:
DATE:
ARTICLE TITLE:
TIME START:
K
W
L
TIME FINISH:
What do I already KNOW
about this topic?
What do I WANT to know
about this topic?
What did I LEARN
after
reading ABOUT this
topic?
I checked the following before reading:
 Headlines and Subheadings
 Italic, Bold, and Underlined words
 Pictures, Tables, and Graphs
 Questions or other key information
I made predictions AFTER previewing the article.
Comments:
Instructor Signature:
Instructional Aide Signature:
23
Ohm’s Law Post Test
NAME:
DATE:
True/False
Indicate whether the sentence or statement is true or false.
____
1. The grounding conductor is one of the two conductors through which normal circuit current
flows.
____
2. The grounded conductor is one of the two conductors through which normal circuit current flows.
____
3. The ungrounded conductor is one of the two conductors through which normal circuit current
flows.
____
4. Voltage does not flow, but is the “pressure” that makes current flow.
Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
____
____
____
____
____
5. What is the term for an amount of charge equal to 6.25 x 1018 electrons?
a. ampere
b. volt
c. coulomb
d. watt
6. The force of electrostatic attraction or repulsion is directly proportional to the product of the two
charges and inversely proportional to the distance between them. This is _____ law.
a. Ampere’s
b. Coulomb’s
c. Ohm’s
d. Volt’s
7. A flow of one coulomb per second past a point in a circuit describes a(n)
a. ampere
b. ohm
c. volt
d. watt
8. The speed of travel of electricity in a conductor is _____ the speed of light.
a. equal to
b. greater than
c. less than
9. In order to have current flow, a circuit must be
a. closed
b. open
c. shorted
d. grounded
24
____ 10. If a circuit is open, current _____ flow.
a. will
b. will not
____ 11. In a circuit, when the two conductors leading from the power source touch metal-to-metal, this is
called a _____ circuit.
a. short
b. grounded
c. open
d. closed
____ 12. The neutral conductor is also referred to as the _____ conductor.
a. hot
b. grounded
c. grounding
d. safety
____ 13. The unit of electromotive force is the
a. ampere
b. ohm
c. volt
d. watt
____ 14. The unit of electrical “pressure” that causes current to flow is called the
a. ampere
b. ohm
c. volt
d. watt
____ 15. The unit of resistance is the
a. ampere
b. ohm
c. volt
d. watt
____ 16. Opposition to current flow is called
a. amperage
b. resistance
c. voltage
d. wattage
____ 17. An opposition to current flow that occurs in alternating current circuits is called
a. current
b. resistance
c. impedance
d. voltage
____ 18. The unit of electrical power is the
a. ampere
b. volt
c. ohm
d. watt
25
____ 19. An electrical device is listed as 3,000 watts. Approximately how many horsepower is this?
a. 1/4
b. 1/6
c. 4
d. 6
____ 20. The statement “current is directly proportional to voltage and inversely proportional to resistance”
is know as _____ law.
a. Ampere’s
b. Coulomb’s
c. Ohm’s
d. Volt’s
____ 21. An electrical circuit has a voltage of 50 V and a resistance of 5 . What is the value of current?
a. 10 A
b. 45 A
c. 55 A
d. 250 A
____ 22. An electric motor is running on 120 V. The current is measured to be 2 A. How many ohms of
resistance is the motor?
a. 60
b. 118
c. 122
d. 240
____ 23. An electric circuit has a resistance of 20  The current is measured to be 6 A. How many volts
are applied to the circuit?
a. 3 1/3
b. 14
c. 26
d. 120
____ 24. A toaster is listed as 1560 W. When it is plugged into a 120 V circuit and starts to make toast,
how many amperes will it draw?
a. 1440
b. 1680
c. 13
d. 187,200
Completion
Complete each sentence or statement.
25. Conventional current flow theory considers electricity to be the flow of charge carriers which are
_______________ in polarity.
26. Electron current flow theory considers electricity to be the flow of charge carriers which are
_______________ in polarity.
26
Ohm’s Law Pre Test
NAME:
DATE:
True/False
Indicate whether the sentence or statement is true or false.
____
1. The grounding conductor is one of the two conductors through which normal circuit current
flows.
____
2. The grounded conductor is one of the two conductors through which normal circuit current flows.
____
3. The ungrounded conductor is one of the two conductors through which normal circuit current
flows.
____
4. Voltage does not flow, but is the “pressure” that makes current flow.
Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
____
____
____
____
____
5. What is the term for an amount of charge equal to 6.25 x 1018 electrons?
a. ampere
b. volt
c. coulomb
d. watt
6. The force of electrostatic attraction or repulsion is directly proportional to the product of the two
charges and inversely proportional to the distance between them. This is _____ law.
a. Ampere’s
b. Coulomb’s
c. Ohm’s
d. Volt’s
7. A flow of one coulomb per second past a point in a circuit describes a(n)
a. ampere
b. ohm
c. volt
d. watt
8. The speed of travel of electricity in a conductor is _____ the speed of light.
a. equal to
b. greater than
c. less than
9. In order to have current flow, a circuit must be
a. closed
b. open
c. shorted
d. grounded
____ 10. If a circuit is open, current _____ flow.
a. will
b. will not
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____ 11. In a circuit, when the two conductors leading from the power source touch metal-to-metal, this is
called a _____ circuit.
a. short
b. grounded
c. open
d. closed
____ 12. The neutral conductor is also referred to as the _____ conductor.
a. hot
b. grounded
c. grounding
d. safety
____ 13. The unit of electromotive force is the
a. ampere
b. ohm
c. volt
d. watt
____ 14. The unit of electrical “pressure” that causes current to flow is called the
a. ampere
b. ohm
c. volt
d. watt
____ 15. The unit of resistance is the
a. ampere
b. ohm
c. volt
d. watt
____ 16. Opposition to current flow is called
a. amperage
b. resistance
c. voltage
d. wattage
____ 17. An opposition to current flow that occurs in alternating current circuits is called
a. current
b. resistance
c. impedance
d. voltage
____ 18. The unit of electrical power is the
a. ampere
b. volt
c. ohm
d. watt
____ 19. An electrical device is listed as 3,000 watts. Approximately how many horsepower is this?
a. 1/4
b. 1/6
c. 4
d. 6
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____ 20. The statement “current is directly proportional to voltage and inversely proportional to resistance”
is know as _____ law.
a. Ampere’s
b. Coulomb’s
c. Ohm’s
d. Volt’s
____ 21. An electrical circuit has a voltage of 50 V and a resistance of 5 . What is the value of current?
a. 10 A
b. 45 A
c. 55 A
d. 250 A
____ 22. An electric motor is running on 120 V. The current is measured to be 2 A. How many ohms of
resistance is the motor?
a. 60
b. 118
c. 122
d. 240
____ 23. An electric circuit has a resistance of 20  The current is measured to be 6 A. How many volts
are applied to the circuit?
a. 3 1/3
b. 14
c. 26
d. 120
____ 24. A toaster is listed as 1560 W. When it is plugged into a 120 V circuit and starts to make toast,
how many amperes will it draw?
a. 1440
b. 1680
c. 13
d. 187,200
Completion
Complete each sentence or statement.
25. Conventional current flow theory considers electricity to be the flow of charge carriers which are
_______________ in polarity.
26. Electron current flow theory considers electricity to be the flow of charge carriers which are
_______________ in polarity.
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