Industry Cluster:
Title of PBL/Inquiry Unit:
Sensors
Electricity:
Series vs. Parallel
Circuits
Grade Level(s):
Academic Content Area(s):
Topic(s):
11th – 12th
Science, Mathematics, & Technology
Physical Sciences, Science and
Technology, Scientific Inquiry,
Scientific Ways of Knowing, Data
Analysis and Probability,
Mathematical Processes
MAIN PROBLEM/ESSENTIAL QUESTION:
Describe the effect adding resistance to a series circuit and to a parallel circuit
has on the current flowing in each circuit.
BIG IDEA(S):
Adding resistance to a series circuit increases the circuit’s total resistance. With a
constant voltage source, the current is reduced as the resistance increases.
Adding resistance to a parallel circuit decreases the circuit’s total resistance resulting in
an increase in current when a constant voltage is applied to the circuit.
The quantitative data collected using a multi-meter is usually somewhat lower than the
theoretical values determined using Ohm’s Law.
It is possible to exceed the “amp” (current) rating of electrical wiring without tripping a
circuit breaker or fuse if loads are added incrementally, such as placing appliances in a
multiple outlet adapter.
Circuit breakers “trip” based on a spike in current that is achieved by a short to ground.
A short to ground causes the resistance to go to zero resulting in the current rising to
infinity instantaneously. This sudden increase in current causes the circuit breaker to
“trip.”
Fuses normally contain a small wire that is gauged for specific amperage (current) to
melt. A short to ground causes a large current through the fuse, melting the wire.
FOCUS QUESTIONS:
1. Explain how adding resistance in series to a series circuit affects the overall
resistance of the circuit and the current flowing in the circuit.
Adding resistance in series to a series circuit increases the overall resistance of the
circuit. This increase in resistance results in a decrease in current when the
voltage is constant.
2.
Explain how adding resistance in parallel to a parallel circuit affects the overall
resistance of the circuit and the current flowing in the circuit.
Adding resistance in parallel to a parallel circuit decreases the overall resistance of
the circuit. This decrease in resistance results in an increase in current in the
circuit when a constant voltage is applied.
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1
3.
How does quantitative data collected using a multi-meter compare to the theoretical
values determined using Ohm’s Law?
Usually the quantitative data is somewhat lower than the theoretical values. This is
mostly due to additional losses within connections and the actual wires.
4.
Can you exceed the “amp” rating (current) of electrical wiring without tripping a
circuit breaker or fuse?
It is possible to exceed the rating on wiring if loads are added incrementally such as
placing appliances in a multiple outlet adapter. This slow addition lacks the short
to ground needed for GFCI (Ground Fault Circuit Interrupter), circuit breaker, or
fuse trips.
5.
How do circuit breakers and fuses work?
Circuit breakers “trip” based on a spike in current that is achieved by a short to
ground. A short to ground causes the resistance to go to zero resulting in the
current rising to infinity instantaneously. This sudden increase in current causes
the circuit breaker to “trip.” Circuit breakers can be easily reset. Fuses normally
contain a small wire that is gauged for specific amperage (current) to melt. A
short to ground causes a large current through the fuse, melting the wire. The
fuse must be replaced to restore the circuit.
PREREQUISITE KNOWLEDGE:
Prior to this activity, the students should be familiar with basic circuitry. This includes
the following:
A basic understanding of series and parallel circuits. In particular, how to wire a set
of light bulbs in series or parallel.
A basic understanding of Ohm’s Law and how to correctly calculate equivalent
resistances in series and parallel circuits. (This activity will reinforce this knowledge.)
The specific operation of a multi-meter, including how to properly place it in the circuit
to monitor current in the circuit.
Proper connection of the multi-meter to avoid “tripping” internal fuses.
The specific operation of computer-based tools, such as Microsoft Excel or other
mathematical analysis program, to be used in evaluating the collected data.
STANDARDS CONNECTIONS:
Content Area:
Science & Mathematics
Science and Benchmark A: Predict how human choices today will determine the
Technology
quality and quantity of life on Earth.
Grade
Standard
Indicator
11
Understanding 1. Identify that science and technology are essential social
Technology
enterprises but alone they can only indicate what can
happen, not what should happen. Realize the latter
involves human decisions about the use of knowledge.
11
Understanding 2. Predict how decisions regarding the implementation of
Technology
technologies involve the weighing of trade-offs between
predicted positive and negative effects on the
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2
environment and/or humans.
11
Understanding 3. Explore and explain any given technology that may have
Technology
a different value for different groups of people and at
different points in time (e.g., new varieties of farm plants
and animals have been engineered by manipulating their
genetic instructions to reproduce new characteristics).
11
Understanding 4. Explain why basic concepts and principles of science and
Technology
technology should be a part of active debate about the
economics, policies, politics and ethics of various sciencerelated and technology-related challenges.
12
Understanding 1. Explain how science often advances with the introduction
Technology
of new technologies and how solving technological
problems often results in new scientific knowledge.
12
Understanding 2. Describe how new technologies often extend the current
Technology
levels of scientific understanding and introduce new areas
of research.
12
Understanding 3. Research how scientific inquiry is driven by the desire to
Technology
understand the natural world and how technological
design is driven by the need to meet human needs and
solve human problems.
12
Understanding 4. Explain why basic concepts and principles of science and
Technology
technology should be a part of active debate about the
economics, policies, politics and ethics of various sciencerelated and technology-related challenges.
Benchmark A: Make appropriate choices when designing and
Scientific
participating in scientific investigations by using cognitive and
manipulative skills when collecting data and formulating conclusions
Inquiry
from the data.
11
Doing Scientific 1. Formulate testable hypotheses. Develop and explain the
Inquiry
appropriate procedures, controls and variables
(dependent and independent) in scientific
experimentation.
11
Doing Scientific 2. Evaluate assumptions that have been used in reaching
Inquiry
scientific conclusions.
11
Doing Scientific 3. Design and carry out scientific inquiry (investigation),
Inquiry
communicate and critique results through peer review.
11
Doing Scientific 4. Explain why the methods of an investigation are based
Inquiry
on the questions being asked.
11
Doing Scientific 5. Summarize data and construct a reasonable argument
Inquiry
based on those data and other known information.
12
Doing Scientific 1. Formulate testable hypotheses. Develop and explain the
Inquiry
appropriate procedures, controls and variables
(dependent and independent) in scientific
experimentation.
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3
12
Doing Scientific 2. Derive simple mathematical relationships that have
Inquiry
predictive power from experimental data (e.g., derive an
equation from a graph and vice versa, determine whether
a linear or exponential relationship exists among the data
in a table).
12
Doing Scientific 3. Research and apply appropriate safety precautions when
Inquiry
designing and/or conducting scientific investigations
(e.g., OSHA, MSDS, eyewash, goggles and ventilation).
12
Doing Scientific 4. Create and clarify the method, procedures, controls and
Inquiry
variables in complex scientific investigations.
12
Doing Scientific 5. Use appropriate summary statistics to analyze and
Inquiry
describe data.
Scientific
Benchmark A: Explain how scientific evidence is used to develop and
Ways of
revise scientific reductions, ideas or theories.
Knowing
11
Nature of
1. Analyze a set of data to derive a hypothesis and apply
Science
that hypothesis to a similar phenomenon (e.g., biome
data).
11
Nature of
2. Apply scientific inquiry to evaluate results of scientific
Science
investigations, observations, theoretical models and the
explanations proposed by other scientists.
11
Nature of
3. Demonstrate that scientific explanations adhere to
Science
established criteria, for example a proposed explanation
must be logically consistent, it must abide by the rules of
evidence and it must be open to questions and
modifications.
11
Nature of
4. Explain why scientists can assume that the universe is a
Science
vast single system in which the basic rules are the same
everywhere.
12
Scientific
7. Explain how theories are judged by how well they fit
Theories
with other theories, the range of included observations,
how well they explain observations and how effective
they are in predicting new findings.
12
Nature of
1. Give examples that show how science is a social
Science
endeavor in which scientists share their knowledge with
the expectation that it will be challenged continuously by
the scientific community and others.
12
Nature of
2. Evaluate scientific investigations by reviewing current
Science
scientific knowledge and the experimental procedures
used, examining the evidence, identifying faulty
reasoning, pointing out statements that go beyond the
evidence and suggesting alternative explanations for the
same observations.
12
Nature of
3. Select a scientific model, concept or theory and explain
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4
Science
how it has been revised over time based on new
knowledge, perceptions or technology.
12
Nature of
4. Analyze a set of data to derive a principle and then apply
Science
that principle to a similar phenomenon (e.g., predatorprey relationships and properties of semiconductors).
12
Nature of
5. Describe how individuals and teams contribute to science
Science
and engineering at different levels of complexity (e.g., an
individual may conduct basic field studies, hundreds of
people may work together on major scientific questions
or technical problem).
Ethical
Benchmark B: Explain how ethical considerations shape scientific
Practices
endeavors.
11
Ethical
5. Recognize that bias affects outcomes. People tend to
Practices
ignore evidence that challenges their beliefs but accept
evidence that supports their beliefs. Scientists attempt to
avoid bias in their work.
11
Ethical
6. Describe the strongly held traditions of science that
Practices
serve to keep scientists within the bounds of ethical
professional behavior.
12
Ethical
No indicators present for this benchmark.
Practices
Science and Benchmark C: Explain how societal issues and considerations affect
Society
the progress of science and technology.
11
Science and
8. Explain that the decision to develop a new technology is
Society
influenced by societal opinions and demands and by cost
benefit considerations.
11
Science and
9. Explain how natural and human-induced hazards present
Society
the need for humans to assess potential danger and risk.
Many changes in the environment designed by humans
bring benefits to society as well as cause risks.
11
Science and
10. Describe costs and trade-offs of various hazards Society
ranging from those with minor risk to a few people, to
major catastrophes with major risk to many people. The
scale of events and the accuracy with which scientists
and engineers can (and cannot) predict events are
important considerations.
11
Science and
11. Research the role of science and technology in careers
Society
that students plan to pursue.
12
Ethical
6. Explain that scientists may develop and apply ethical
Practices
tests to evaluate the consequences of their research
when appropriate.
12
Science and
7. Describe the current and historical contributions of
Society
diverse peoples and cultures to science and technology
and the scarcity and inaccessibility of information on
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some of these contributions.
12
Science and
8. Recognize that individuals and society must decide on
Society
proposals involving new research and the introduction of
new technologies into society. Decisions involve
assessment of alternatives, risks, costs and benefits and
consideration of who benefits and who suffers, who pays
and gains, and what the risks are and who bears them.
12
Science and
9. Recognize the appropriateness and value of basic
Society
questions "What can happen?" "What are the odds?" and
"How do scientists and engineers know what will
happen?"
12
Science and
10. Recognize that social issues and challenges can affect
Society
progress in science and technology.(e.g., Funding
priorities for specific health problems serve as examples
of ways that social issues influence science and
technology).
12
Science and
11. Research how advances in scientific knowledge have
Society
impacted society on a local, national or global level.
Mathematics Standards and Benchmarks
11 & 12 Data Analysis Benchmark A: Create and analyze tabular and graphical
and probability
displays of data using appropriate tools, including
spreadsheets and graphing calculators.
11 & 12 Data Analysis Benchmark D: Connect statistical techniques to
and probability
applications in workplace and consumer situations.
11 & 12 Mathematical Benchmark B: Construct logical verifications or counterProcesses
examples to test conjectures and to justify or refute
algorithms and solutions to problems.
11 & 12 Mathematical Benchmark C: Assess the adequacy and reliability of
Processes
information available to solve a problem.
11 & 12 Mathematical Benchmark F: Present complete and convincing
Processes
arguments and justifications, using inductive and
deductive reasoning, adapted to be effective for various
audiences.
11 & 12 Mathematical Benchmark G: Understand the difference between a
Processes
statement that is verified by mathematical proof, such as
a theorem, and one that is verified empirically using
examples or data.
11 & 12 Mathematical Benchmark H: Use formal mathematical language and
Processes
notation to represent ideas, to demonstrate relationships
within and among representation systems, and to
formulate generalizations.
11 & 12 Mathematical Benchmark I: Communicate mathematical ideas orally
Processes
and in writing with a clear purpose and appropriate for a
specific audience.
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11 & 12
Mathematical
Processes
Benchmark J: Apply mathematical modeling to workplace
and consumer situations, including problem formulation,
identification of a mathematical model, interpretation
Summary:
Students will investigate what happens to circuit current in a parallel circuit as resistance
is added. This knowledge will be used to help determine a cause as to why fires have
developed in homes within their fictitious neighborhood.
Students will construct a parallel circuit using light bulbs, wire and a 6-V battery.
Students will determine the resistance of each bulb individually and collectively in the
circuit. The multi-meter will measure the resistance of the components and also
monitor the current of the circuit as resistance is added in parallel.
TECHNOLOGY CONNECTION:
Thermal imaging can be used to find hot spots in walls where excessive current may be
flowing. In addition, an infrared thermometer can be used to check surface
temperatures of walls from a safe distance.
Automatic monitoring of circuits via remote sensing can be utilized to determine if
current changes within the circuit are within limits or exceeding design limits. Remote
sensing allows for monitoring of multiple circuits from a central location reducing
manpower needs and resources.
Integration Model
Application Description
A Technology that supports students and
teachers in adjusting, adapting, or
augmenting teaching and learning to
meet the needs of individual learners or
groups of learners
D Technology that supports students and
Multi-meter - measure the resistance
teachers in dealing effectively with
of the components
data, including data management,
Multi-meter - monitor the current of
manipulation, and display
the circuit
Excel – for data tables and graphs
I Technology that supports students and
Research the National Electric Code
teachers in conducting inquiry, including
the effective use of Internet research
methods
S Technology that supports students and
Battery and bulbs to model house
teachers in simulating real world
wiring
phenomena including the modeling of
physical, social, economic, and
mathematical relationships
C Technology that supports students and
MS Word – Letter writing
teachers in communicating and
collaborating including the effective use
of multimedia tools and online collaboration
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Interdisciplinary Connection:
Science –Technology – Writing – Presenting
Home Connection:
Students could research the National Electric Code and home wiring diagrams to get an
overview of how homes are wired.
The students could also be encouraged to perform some observations of their current
homes by recording circuit breaker information and determining the number of circuits
in their house and the current rating for each circuit.
Differentiated Instruction (Process, Product, or Content):
Suggestions for opportunities to differentiate instruction during the activity/unit. Actual
differentiation will be at the individual teacher’s discretion.
For differentiation through process, use grouping and regrouping based on content,
project, and assessments.
For differentiation of product, vary the expectations and requirements of individual
students based on ability.
For differentiation of content, the teacher should address the same concepts with all
students but adjust the degree of complexity based on the range of student abilities.
Overview:
In this activity the students are presented with a scenario related to home ownership.
Scenario:
You are a new homeowner in a new development. Recently there have been several
fires in your neighbors’ new homes. You have also become aware of two residents in
your new development receiving fatal shocks from circuits within their homes.
The development you reside in is new with approximately 100 single family homes. All
homes were built by the same construction company, but some jobs were
subcontracted out. You find out that 3 different electrical companies wired the homes
in your development. Upon further investigation you find the same company wired
the homes that had fires and where the fatalities occurred. You speculate that an
electrician must have wired the homes incorrectly. What do you suspect is the
problem?
You will investigate what happens to a circuit’s current as resistance is added in series
and in parallel. After conducting your investigation you will write a brief letter
outlining your findings and identifying where you believe the electrical problems exist.
Your letter must be addressed to the City Planning Commission. You must also
identify yourself as a resident in the development, your concern over the electrical
problems, your belief as to the cause, and a recommendation for correction. You can
include any monetary awards as compensation for those who have suffered and
temporary accommodations needed to ensure the safety of you and your neighbors.
Preparation for activity:
Check all the multi-meters for proper function; specifically, make sure the ammeter
portion is operating correctly.
Critical Vocabulary:
Ohm’s law - current flowing through a portion of a circuit equals the voltage difference
across that portion divided by the resistance.
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8
voltage - a change or difference in electric potential measured in volts.
electric current - the rate of flow of electric charge.
resistance – the property in a component in a circuit of opposing the flow of electric
current and generating heat.
series circuit – a circuit connected in single loop, so that current passes through each
component in succession.
parallel circuit – a circuit with elements connected by more than one path so that the
current divides and rejoins.
directly proportional – a change in one variable leads to a change in another variable
in the same direction, if one increases the other increases, if one decreases the other
decreases.
inversely proportional – a change in one variable leads to an opposite change in
another variable, if one increases the other decreases.
circuit – a closed or complete path for an electric current.
electromotive force (emf) – potential energy per unit of charge produced by a battery
or other source of electric energy. The name is misleading, because it is a potential
difference, or voltage – not a force.
resistor – a component in an electric circuit that opposes the flow of electric current.
conductor – a material that readily allows charge to flow.
insulator – a material that does not ordinarily permit a flow of charge through it.
ammeter – an instrument for measuring electric current.
positively charged – an object with a deficit of electrons.
negatively charged – an object with a surplus of electrons.
direct current – electric current that flows in a single direction.
alternating current – electric current that continually reverses its direction.
Timeframe:
Day
Time Allotment Activities
1
40 minutes
Lab-Data collection
2
40 minutes
Lab-Data collection
3
40 minutes
Data analysis and letter preparation
Materials & Equipment:
Multi-meter (to measure resistance, voltage, and current)
Circuit board (optional)
4 light bulbs
6-V Lantern Battery
Wires
Alligator clips (optional - can be used to aid in connection and reduce assembly time)
Safety & Disposal:
No special disposal required except when 6-V batteries are no longer usable.
Pre-Test:
Grade Level: High School
1. There are two types of charges, positive and negative
a. Negative charges move
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9
b. No charges move
c. Positive charges move
d. Positive and negative charges move
2. The key principle to remember about charges is
a. Opposite charges move and like charges do not
b. Like charges move and opposite charges do not
c. Like charges attract and opposite charges repel
d. Like charges repel and opposite charges attract
Short Answer
3. Write the formula for Ohm's Law.
Give the meaning of each letter, write the respective unit of measure, and symbol.
Define each of the following terms using complete sentences.
4. electric current5. alternating current6. ammeterFind the value of the current(s) in each circuit below. Show your work.
7.
8. I
A
175 Ω
40 Ω
6 v
20 V
IC
220 V
25 Ω
I
60 Ω
IB
Extended Response
10. Explain the behavior of current in a series circuit as more resistance is added in
series to the circuit. Explain the behavior of current in a parallel circuit as more
resistance is added in parallel to the circuit. In both cases the voltage supplied to
the circuit is constant. Provide a mathematical example for each case that supports
your explanation.
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Pre-Test Rubric:
1. There are two types of charges, positive and negative
e. Negative charges move
f. No charges move
g. Positive charges move
h. Positive and negative charges move
2. The key principle to remember about charges is
a. Opposite charges move and like charges do not
b. Like charges move and opposite charges do not
c. Like charges attract and opposite charges repel
d. Like charges repel and opposite charges attract
Short Answer
3. Write the formula for Ohm's Law. V = R*I
Give the meaning of each letter, write the respective unit of measure, and symbol.
V- voltage
volts
V
R- resistance
ohms
Ω
I- current
amperes
A
Define each of the following terms using complete sentences.
4. electric current - Electric current is the rate of flow of electric charge.
5. alternating current - Alternating current is electric current that continually reverses
its direction.
6. ammeter - An ammeter is an instrument used for measuring electric current.
Find the value of the current(s) in each circuit below. Show your work.
7.
8.
IA
175 Ω
40 Ω
6 v
IC
20 V
220 V
25 Ω
60 Ω
I
I=0.1 A or 100 mA
IB
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11
IA=5.5 A
IB=3.67A
IC=9.17A
Extended Response
10. Explain the behavior of current in a series circuit as more resistance is added in
series to the circuit. Explain the behavior of current in a parallel circuit as more
resistance is added in parallel to the circuit. In both cases the voltage supplied to
the circuit is constant. Provide a mathematical example for each case that supports
your explanation.
Resistance added to a series circuit increases the overall resistance of the series
circuit that causes the current to decrease when supplied by a constant voltage
source. Resistance added in parallel decreases the overall resistance of the parallel
circuit that causes an increase in current in the circuit when a constant voltage
source is used.
A series circuit with three 3-Ω resistors and a 9-V source results in
RT = 3Ω + 3Ω + 3Ω = 9Ω
A parallel circuit with the same resistors and source results in
Short-Answer Rubric:
Short-answer items require a brief written response. Student responses receive a score
of 0, 1 or 2 points.
Score
Point 2
The student’s response has Ohm’s law correctly written as a
formula. Each term is correctly identified for meaning, units and
symbol.
Score
Point 1
The student’s response has Ohm’s law correctly written as a
formula. Some, but not all of the terms are identified for
meaning, units, and symbol.
Score
Point 0
The student’s response does not have Ohm’s law correctly written.
The meaning of each term, units, or symbol is incorrect or
missing.
Pre-Activity Discussion:
Discuss/Review Prerequisite Knowledge indicated above.
Students are required to conduct an investigation to determine what may be occurring
in the new homes that could cause the fires.
Students could research the National Electric Code and home wiring diagrams to get an
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overview of how homes are wired.
The students could also be encouraged to perform some observations of their current
homes by recording circuit breaker information and determining the number of
circuits in their house and the current rating for each circuit.
Instruct students on the proper method of connecting a meter to an unknown quantity.
Make sure the highest scale is used to ensure the fuses internal to the meter are not
blown.
Assignment of Student Roles and Responsibilities:
Students will all assume the same role:
Role Name
New Home Owner
Brief Description You are a new homeowner in a new development. Recently there
have been several fires in your neighbors’ new homes. You have
also become aware of two residents in your new development
receiving fatal shocks from circuits within their homes.
Activity:
Teacher instructions:
Have students assemble a parallel circuit as well as draw the circuit diagram to reinforce
the multiple paths current can flow in a parallel circuit.
Schedule a field trip to AFRL remote sensing section to view thermal imaging state of the
art equipment. If not available consider contacting a local fire department that uses
thermal imagers to locate people inside of smoke filled buildings.
Activity Scenario: Make copies or change to suit your particular needs/interests.
Student instructions:
Scenario:
You are a new homeowner in a new development. Recently there have been several
fires in your neighbors’ new homes. You have also become aware of two residents in
your new development receiving fatal shocks from circuits within their homes.
The development you reside in is new with approximately 100 single family homes. All
homes were built by the same construction company, but some jobs were
subcontracted out. You find out that 3 different electrical companies wired the homes
in your development. Upon further investigation you find the same company wired
the homes that had fires and where the fatalities occurred. You speculate that an
electrician must have wired the homes incorrectly. What do you suspect is the
problem?
You will investigate what happens to a circuit’s current as resistance is added in series
and in parallel. After conducting your investigation you will write a brief letter
outlining your findings and identifying where you believe the electrical problems exist.
Your letter must be addressed to the City Planning Commission. You must also
identify yourself as a resident in the development, your concern over the electrical
problems, your belief as to the cause, and a recommendation for correction. You can
include any monetary awards as compensation for those who have suffered and
temporary accommodations needed to ensure the safety of you and your neighbors.
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Purpose: Investigate parallel and series circuitry to determine a possible cause for the
fires in the new houses. Explore and collect data from a parallel circuit as resistance
is added to the circuit. Determine what happens to overall circuit resistance and
overall circuit current as these resistances are added. Based on this lab and your
knowledge, extend the process theoretically to a series circuit.
Use four light bulbs arranged in a parallel circuit. Use a (Kelvin 300LE Digital) Multimeter to find resistance and current as required in each step below.
1. Using the Kelvin 300LE Digital Multi-meter on the appropriate scale, find the
resistance of each light bulb. Fill in the table below.
NOTE: Place the black probe in the COM port and the red probe in the VΩA port. Turn
the multi-meter to the Ω scale.
Table 1
Light Bulb
Resistance (Ω)
1
2
3
4
2. Calculate the total resistance of the parallel circuit using the values you found in the
table above.
3. Wire all four bulbs in the parallel circuit. Using the Kelvin 300LE Digital Multi-meter,
find the total resistance of the circuit.
4. Compare your calculated value to the value found using the Kelvin 300LE Digital
Multi-meter. Are the values the same? What could contribute to the difference in
the calculated value and the value found using the Kelvin 300LE Digital Multi-meter?
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14
5. Based on the calculated total resistance found in #2 above calculate the current
flowing in the circuit when a 6-Volt battery is used as the power source. Show your
work.
6. Based on the value found for total resistance using the Kelvin 300LE Digital Multimeter calculate the current flowing in the circuit when a 6-Volt battery is used as the
power source. Show your work. Enter your calculated value in Table 2 below.
7. Do the values for current in #5 and #6 above agree? What could contribute to the
difference in the calculated value and the value found using the Kelvin 300LE Digital
Multi-meter?
8. Calculate the current through each bulb based on the values for resistance recorded
in Table 2. Show your work. Record the value of calculated branch current in Table
3.
Light Bulb
1
2
3
4
Circuit
Table 2
Calculated Current (A)
Measured Current (A)
NOTE: Place the red probe in the 10A port prior to collecting any data related
to current. Use the 10A scale on the Kelvin 300LE Digital Multi-meter for all
current measurements. The Kelvin 300LE Digital Multi-meter must be in
series in the circuit to measure current.
9. Measure the current through each bulb individually and the entire circuit. Record the
values in Table 2 above.
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15
10. Do the calculated and measured current values agree? What could account for the
difference in the readings?
11. How do the resistance and current change as you increase the number of bulbs
wired in parallel? Complete the table below with one bulb in the circuit, then two in
the circuit, and so on. Use the Kelvin 300LE Digital Multi-meter as you have in the
other parts of this lab.
Table 3: Parallel Circuit
Number of Bulbs in
Total Resistance
Circuit
(Ω)
1
2
3
4
Total Current
(A)
YOU MUST COMPLETE THROUGH STEP 11 IN CLASS.
12. How would the results of this experiment have been different if the light bulbs had
been wired in series? Write your battery voltage on each of the four circuit diagrams
below. Determine the total resistance and current if there is one light bulb. Repeat
this for two, three, and four IDENTICAL light bulbs.
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Table 4: Series Circuit
Number of Bulbs in
Total Resistance
Circuit
(Ω)
1
2
3
4
Total Current
(A)
13. Using Excel, make four graphs using the data from Tables 3 & 4. Each graph should
have the appropriate trendline (linear or power depending on the shape of the
graph), the equation of the trendline, and an appropriate title for the graph and its
axes. For all of the graphs, the x-coordinate should be the number of light bulbs.
The y-coordinates of the graphs should be . . . .
a. Resistance of the parallel circuit
b. Current of the parallel circuit
c. Resistance of the series circuit
d. Current of the series circuit
14. After conducting your investigation you will write a brief letter outlining your findings
and identifying where you believe the electrical problems exist. Your letter must be
addressed to the City Planning Commission. You must also identify yourself as a
resident in the development, your concern over the electrical problems, your belief
as to the cause, and a recommendation for correction. You can include any
monetary awards as compensation for those who have suffered and temporary
accommodations needed to ensure the safety of you and your neighbors. Include
and discuss the appropriate graph(s) as evidence of your findings.
Have one adult read your letter and sign below before you submit it.
The adult that read my letter is ____________________________________.
Instructional tips:
If time is short teachers may use preassembled circuit boards with an array of 4 light
bulbs in parallel.
How to Make an X-Y Scatter Plot
1) Enter Data
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2)
Highlight the data you want to graph
If
•
•
•
the data you need is not in consecutive columns . . . .
highlight the first column
hold down control
highlight the second column
3)
Choose Insert, Chart from the Insert menu
4)
Choose x-y scatter and hit next
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5)
If the chart looks like it should, hit next. If not, ask for help.
6)
Add a title for the graph and the axes. The titles that Excel suggests are almost
always unacceptable. Make your own titles. Hit next when you are done.
7)
Save your chart as a new sheet and hit finish.
How to Add a Trendline (Best-fit Line) to a Scatter Plot
After making the graph, click
on the chart. Choose the
Chart menu, Add Trendline
Right click on one of the points and
choose Add Trendline.
OR
Choose linear if it looks linear or power
if it does not.
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Then, click the options tab. Click the
“Display equation on chart” box.
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The trendline and its equation should appear.
Formative Assessments:
Teacher should be walking around and observing the care that is being taken in
fabricating the circuits, measuring resistance, and measuring the current along with
collecting and recording data.
All students should be participating in their groups.
Summative Assessment:
Rubric
Lab Packet
Statement of
Cause
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Outstanding
All items - lab
packet, letter, four
graphs - are
complete and
submitted on
time.
70 points
Good
All items - lab
packet, letter, four
graphs - are
complete and
submitted one day
late.
50 points
Minimal
All items - lab
packet, letter, four
graphs - are
complete and
submitted two
days late.
30 points
Failing
One or more items
are more than two
days late.
Identifies cause
and begins
development of a
corrective action
plan.
Can identify the
cause with
minimal coaching
or assistance.
Needs moderate
coaching and
assistance to
identify the cause.
Needs extensive
coaching and
assistance to
identify the cause.
10 points
8 points
6 points
0 points
0 points
20
Evidence Used to
Support
Statement of
Cause
Recommendation
for Correction
Immediately
identifies and
evaluates
appropriate data
and graphs
supporting the
corrective action
plan.
Identifies and
evaluates data
and graphs
needed to support
a corrective action
plan with minimal
coaching or
assistance.
Needs moderate
coaching and
assistance in
identifying and
evaluating data
and graphs
needed to support
the corrective
action plan.
Needs extensive
coaching and
assistance in
identifying and
evaluating data
and graphs
needed to support
the corrective
action plan.
10 points
8 points
6 points
0 points
Completes
corrective action
plan with minimal
assistance.
Checks and
determines
reasonableness of
solution with
minimal
assistance.
Completes
corrective action
plan with
moderate
assistance.
Checks and
determines
reasonableness of
solution with
moderate
assistance.
Cannot or does
not complete
corrective action
plan without
extensive
assistance.
Unable to check or
determine
reasonableness of
solution without
extensive
assistance
8 points
6 points
0 points
All identified
problems
corrected by the
second submittal.
Two or fewer
errors after
second submittal.
More than two
errors after
second submittal.
6 points
0 points
The graph was
submitted with
only one error
when they were
compared with the
"Graph Checklist."
More than one
error.
6 points
See above
6 points
See above
6 points
0 points
See above
0 points
See above
0 points
Corrective action
plan completed
with
recommendation(s
) for
implementation.
Evaluates and
determines
reasonableness of
solution and can
apply results to
other situations.
10 points
Format and
grammar of letter
Quality of Graph 1
Quality of Graph 2
Quality of Graph 3
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There are no
grammatical or
usage errors
(spelling,
punctuation,
incomplete
sentences, there
vs. their, etc.)
present. There
are no unclear
sentences.
10 points
Your graph is
completed in
accordance with
the "Graph
Checklist" below.
10 points
See above
10 points
See above
10 points
8 points
Your graph is
completed in
accordance with
the "Graph
Checklist" after
the second
submittal.
8 points
See above
8 points
See above
8 points
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Quality of Graph 4
See above
10 points
See above
8 points
See above
6 points
See above
0 points
Does your graph have . . . .
a title that tells the viewer the type of circuit that is studied?
have the x-axis labeled? have the units included?
have the y-axis labeled? have the units included?
have a trendline?
have the equation of the trendline labeled?
Post-Activity Discussion:
Make certain students made the connections you intended them to make through the
activity/unit.
Will students be asked to write about their reflections or will they be expressed orally?
Will you employ other approaches such as concept maps?
Post-Test:
1. There are two types of charges, positive and negative
i. Negative charges move
j. No charges move
k. Positive charges move
l. Positive and negative charges move
2. The key principle to remember about charges is
a. Opposite charges move and like charges do not
b. Like charges move and opposite charges do not
c. Like charges attract and opposite charges repel
d. Like charges repel and opposite charges attract
Short Answer
3. Write the formula for Ohm's Law.
Give the meaning of each letter, write the respective unit of measure, and symbol.
Define each of the following terms using complete sentences.
4. electric current5. alternating current6. ammeterFind the value of the current(s) in each circuit below. Show your work.
7.
8. I
A
175 Ω
40 Ω
6 v
20 V
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IC
22
Extended Response
9. Explain the behavior of current in a series circuit as more resistance is added in series
to the circuit. Explain the behavior of current in a parallel circuit as more resistance
is added in parallel to the circuit. In both cases the voltage supplied to the circuit is
constant. Provide a mathematical example for each case that supports your
explanation.
Rubric:
Electricity
Post-Test (High School) KEY
1.
Ohm’s law states that V=IR which means:
a. If voltage is constant current and resistance are inversely proportional.
b. If voltage is constant current and resistance are directly proportional.
c. If current is constant voltage increases without limit when resistance increases.
d. If current is constant resistance increases without limit when voltage increases.
2.
Parallel circuit equivalent resistance is found by:
a. Summing the resistances.
b. Summing the reciprocals of the resistances.
c. Summing the reciprocals of the resistances and taking the inverse.
d. Summing the largest and smallest resistances only.
Short Answer
3.
Write the formula for Ohm's Law
V = R*I
Give the meaning of each letter, write the respective unit of measure, and symbol.
Meaning
Units
Symbol
V- voltage
volts
V
R- resistance
ohms
Ω
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I- current
amperes
A
23
Define each of the following terms using complete sentences.
7. electric current- Electric current is the rate of flow of electric charge.
8. alternating current- Alternating current is electric current that continually reverses its
direction.
9. multi-meter- A multi-meter is an instrument used for measuring voltage, electric current, and
resistance.
Find the value of the current(s) in each circuit below. Show your work.
IA
7.
8.
175 Ω
40 Ω
IC
20 V
220 V
25 Ω
60 Ω
I
I=0.1 A or 100 mA
IB
IA=5.5 A
IB=3.67A
IC=9.17A
Extended Response
9. Explain the behavior of current in a series circuit as more resistance is added in series to the
circuit. Explain the behavior of current in a parallel circuit as more resistance is added in parallel
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to the circuit. In both cases the voltage supplied to the circuit is constant. Provide a mathematical
example for each case that supports your explanation.
Resistance added to a series circuit increases the overall resistance of the series circuit that causes
the current to decrease when supplied by a constant voltage source. Resistance added in parallel
decreases the overall resistance of the parallel circuit that causes an increase in current in the
circuit when a constant voltage source is used.
A series circuit with three 3 Ω resistors and a 9 V source results in R 3Ω+3Ω+3Ω=9 Ω
A parallel circuit with the same resistors and source results in
Rubric:
Short-answer items require a brief written response. Student responses receive a score
of 0, 1 or 2 points.
Score
Point
2
The student’s response has Ohm’s law correctly written as a formula.
Each term is correctly identified for meaning, units and symbol.
Score
Point
1
The student’s response has Ohm’s law correctly written as a formula.
Some, but not all of the terms are identified for meaning, units,
and symbol.
Score
Point
0
The student’s response does not have Ohm’s law correctly written.
The meaning of each term, units, or symbol is incorrect or missing.
Extension:
This activity provides students will a solid foundation in circuit analysis and how
resistance and current are coupled within a circuit. Students can use this knowledge
for simple home repairs, simple car repairs, and as a basis for learning more complex
circuitry.
Career Connection:
Electrical Engineering
Note: This activity is directly related to activities found within the electrical engineering
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tech prep and computer information technology tech prep programs.
Additional Resources:
Purpose and Application
Resources that support the content of this
activity/unit.
Resources that support the methods of
instruction within this lesson.
Teacher Reflection:
Were students focused and on task throughout the lesson?
If not, what improvements could be made the next time this lesson is used?
Were the students led too much in the lesson or did they need more guidance?
How did students demonstrate that they were actively learning?
Did you find it necessary to make any adjustments during the lesson?
What were they?
Did the materials that the students were using affect classroom behavior or
management?
What were some of the problems students encountered when using the …?
Are there better items that can be used next time?
Which ones worked particularly well?
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Additional Comments:
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