Electric Circuits Unit Plan
by Tamara Kohnen
completed in partial fulfillment of the requirements for
"Teaching High School Physics"
Physics 301
Autumn 1996
Illinois State University
Carl J. Wenning, Instructor
I. UNIT OVERVIEW
A. In this unit the student will explore the topic of electricity. Specifically, electric circuits will be the topic of consideration. Using a conceptual and historical approach, the students will gain a view of the "big picture" in electricity and the backgrounds of some of the scientists responsible for the development of circuits. Some procedures that will be used to accomplish these goals are inquiry, concept change, and cooperative learning. Some of the many advantages of cooperative learning include individual accountability, group accountability, positive interdependence, and improvement of social skills. Another procedure that will be used is a conceptual change lesson. During this lesson, students will be forced to confront any preconceptions they may have about a concept. This allows the students to be involved in the learning process by recognizing what they do or do not already know. An inquiry lesson will also be used to get students involved. This activity can be either mental or physical. Regardless, the students are forced to think about the concepts and apply the scientific process while doing so. During this unit, the student will gain the processes necessary to apply the content to real-life situations. This thinking process will allow the student to work through situations similar to those worked in class. He/She will have a better understanding of how objects around them work. Possibly, the student can then go on to more advanced science courses with the necessary background knowledge. The intended students for this unit plan are high school juniors and seniors who are enrolled in a standard physics course. Prerequisites will include a math background and some understanding of currents. The textbook used in the unit is Physics by Genzer and Youngner.
B. Some overall goals of this unit plan include a clear understanding of electric circuits, how they are used in everyday life, and the application of processes that allow the student to research this topic. These guidelines meet national and state standards as they incorporate the use of technology in the form of computers to develop and apply science skills. The student should be able to conduct a scientific experiment in which he/she can collect and interpret data to reach a conclusion.
C.
1. Once the students are able to understand and relate these concepts to everyday life, they will be able to further develop and apply them to more difficult concepts. By learning about electric circuits, the student can better understand some of the many appliances that are found in typical households which involve the use of this topic.
2. Society benefits from the knowledge of electric circuits by the ability to minimize the cost required to operate some of the appliances. Familiarity of electric circuits and how they work can lead to the minimization of energy required to use some of these appliances.
3. The profession can benefit from electric circuits because they are included in forms of research.
II. RELATIONSHIP OF UNIT TO COURSE CURRICULUM
A. General outline of year-long curriculum
Unit Topic Concepts Time
I Measurement distance, speed, force, 8 wk
acceleration, vectors, work
II Motion and Energy fluids, potential energy, 6 wk
kinetic energy
III Lights and Optics reflection, dispersion, light 6 wk
particles, light waves
IV Wave Motion sound waves, acoustics 6 wk
V Heat temperature, transfer, 8 wk
heat engines, refrigeration,
air conditioning
VI Electricity and Magnetism electric circuit, current 9 wk
generators, motors
Unit Historical Character Concepts Time
I Newton force, cause of motion 8 wk
II Rumford heat 8 wk
III Einstein relativity 8 wk
B. There are many activities that can be used to improve student skills and dispositions. Some of the activities planned for this unit are discussed here. One such activity is an inquiry-based lab in which the student is responsible for the derivation of Ohm's Law. Another activity requires the student to solve a black box circuit puzzle in a cooperative learning environment. Several of the lessons planned for this unit include inquiry and cooperative learning. These lessons result in improved social skills, independence, and the responsibility of learning. As a result of this course, the student will develop process skills that can be used to analyze many types of situations. The student should be aware that science is never accepted as a final draft and he/she should be skeptical of any findings. Physics offers an excellent opportunity to exercise critical thinking. Each situation is unique and the student must first assess the situation and develop a plan of action before attempting to solve it. This type of behavior is also useful outside of the classroom. A responsible adult should act in the same manner when approached with any type of problem.
III. CONTENT OUTLINE
A. Definitions
1. Current
2. Voltage
3. Ohm's Law
4. Circuits
a. Parallel resistors
b. Series resistors
B. Graphical Representations
1. Ohm's Law
a. Current v resistance
b. Voltage v resistance
2. Current
a. Direct
b. Alternating
C. Technology
1. Computers
2. Circuit puzzles
3. Circuit boards
4. VOM
IV. MAJOR OBJECTIVES
A. By the end of this unit, the student should be able to identify the components of a circuit and the relationships that occur between them. In addition, the student should be able to "follow" the flow of current and make predictions about the activity in a circuit at a particular position.
B. By the end of this unit, the student should be able to utilize all variables associated with Ohm's Law (V, I, R). The student should also be able to manipulate this equation as it applies to different situations. The use of technology should become an integrated tool to collect and analyze data. In addition, the student should be able to gather data to construct a graph and interpret the meaning of the graph.
C. The student should demonstrate a "proper" scientific attitude when approaching activities. Some aspects of this attitude includes enthusiasm, cooperation, and appropriate ethics regarding the results of an activity (i.e. altering of data. etc.). The student should be logical in the development of an approach. When conducting an experiment, the student should remain objective and be critical when evaluating the data. Once a conclusion is reached, the student should be skeptical and aware of other possible solutions. I will try to achieve this goal by setting an example and stressing the importance of process skills. Reinforcement of the scientific process will remind the student of his/her expectations.
V. ALTERNATIVE CONCEPTIONS
Gabel, D.L. (1994). Handbook of research on science teaching and learning. New York, NY: MacMillan.
Five versions of a distinct model were used for this research to identify various preconceptions among children. One of the most popular preconceptions was called the "single-wire" notion. This idea is the belief that current travels through one wire from a battery to a bulb. This bulb served as a type of electricity "sink." Another popular misconception was discovered through the "clashing-currents" model. In this model, electricity leaves both terminals of the battery and travels toward the bulb, where it is "used up.î More preconceptions were identified in the "unidirectional" models. Three that were mentioned in this section were "unidirectional without conservation," "unidirectional with sharing," and "unidirectional with conservation."
These preconceptions differ in age groups. Younger children tend to believe in the single-wire model. Children in their middle years usually believe in the "clashing-current" model. This method is gradually replaced by the "unidirectional" models. The notion of conservation becomes somewhat evident to about 10 percent of the children at age 12 and rises to about 60 percent acceptance by age 18.
VI. CLASSROOM METHODS
Arons, A.B. (1990). A guide to introductory physics teaching. New York, NY: John Wiley & Sons.
A. See appendix for copies of title page and table of contents.
B. Though a circuit is common in many households, it is a difficult subject for many people to fully understand. The notion that electricity is "used up" is prevalent in the minds of many. In many cases, this topic is simply glossed over without much detail. More thought-provoking questions such as "How do we know...?" and "Why do we believe...?" need to be considered.
A big debate among many physics teachers is the question "Which should come first, static or current electricity?" Arons says that this should be the preference of the teacher. However, one should be sure to include the connections between the two.
It is difficult for students to make the connection between household items such as outlets and batteries and frictional phenomena. It is not obvious that these circuits involve "charge in motion." The student should think about how this occurs and be able to apply it elsewhere. The charging of capacitor plates is one method that can be used to demonstrate the concepts of charge, conductor, nonconductor, leakage of charge, electrostatic inductance, and polarization.
An experiment in which undergraduate nonscience majors were given a dry cell, a length of wire, and a light bulb and asked to get the bulb to light showed some preconceptions associated with electric circuits. After 20-30 minutes, one member of the group succeeded by trial and error. When the same experiment was performed with seven year-old children, the results were the same in the same amount of time. Continuous exposure to the problem allowed the group of adults to become more familiar with the circuit and understand it better. The ability to study each component, including the makeup of the light bulb, allowed the students to better understand what was happening. This information should not be assumed to be common knowledge among all students.
Research shows that very few students, even those in engineering- physics courses, develop sound understanding of what happens in a circuit. Many were familiar with the basis of the circuit, but they could not predict what will happen to the current at various points of the circuit. Students can be taught to change this misunderstanding if they are given the chance to practice reasoning. This may be done with simple configurations of batteries and bulbs. This can be given as homework since the equipment is readily available at many stores. There are many situations which the students can study. Some of these include "adding resistance", "short circuits", and ì potential difference.î
Arons gives a short history on the development of Ohm's Law, but clarifies that he does not advocate this above other approaches. He explains how Ohm's research did not directly lead to what we know as Ohm's Law. In addition work by Mayer, Joule, and Helmholtz led Kirchhoff to point out the relationship that we call Ohm's Law.
The order that voltage, current, and resistance are presented is another controversy. The most common approach is to introduce R = V/I. This relationship can be described using all of the variables.
The idea that electric current in metals is a bulk phenomenon is one that few textbooks address. How do we know that this is true? Students should be led to consider this question and to consider how it might be resolved.
The idea of current as a "flow of electrons" is something that leaves many students confused. This idea is not clarified to consist only of metallic conduction. The students are simply given definitions and are not taught how to apply those definitions correctly. Arons suggests that it is wiser to teach students the positive current convention. Some reasons include that it underlies the definitions of electric field strength and potential energy, the treatment of capacitive and inductive circuit elements, and the standard notation in diagrams of electronic circuits.
Many students do not realize that Ohm's law does not apply in every situation in which a source of potential difference drives an electric current (i.e. running a motor, charging a battery). Just telling students this is not very successful. A more effective way of getting this idea across to the students is the question of why power emission is far more efficient at high voltages than at low. This allows the student to learn this idea in a more memorable context and to be able to connect it to engineering and societal conditions.
Electrons exist as free entities in metals. This is usually taught in an authoritarian manner. For example, we know this because scientists have told us so. This topic does have to be taught in this manner. It should be taught by first introducing the electron and some of their properties. One has to realize that electrons are free carriers of charge in metals. This can done by showing Thompson's work with the cathode ray tube. All of the equations can be derived through experiments. Though this may be difficult for many students to visualize, Arons suggests it as an excellent exercise for honors students.
C. Lesson plans
1. Concept change/constructivist lesson
Objective: The students will identify misconceptions that are associated with both magnetism and currents.
Content: There is no content which will applied to this lesson.
Instructional Activities:
1) Behavioral objective: Introduce the demonstration and show how it works.
2) Have the students attempt to explain what is happening.
3) Appoint a student to write all possible explanations on the board.
4) Discuss each possibility and why or why not it is possible.
5) Ask a student to explain the science of the demonstration to me.
A. The first demonstration will involve placing magnetic rings on a glass bar. By alternating the direction of the rings, the rings will repel and have a space between them. When the students try, the expected reaction will involve the rings attracting and clinging together if the students don't realize that the direction is changed.
B. The second demonstration will involve two similar rings that are placed on an iron rod which is in the center of a coil. One of the rings is suspended around the rod when the machine is turned on. The other ring does not change when the machine is turned on. The students will perform the above activities.
Objective: The goal of this inquiry lab is to involve students in activities that will lead to the development of Ohm's Law.
Introduction: Give a brief explanation of desired goal and explain directions and safety factors.
We have been talking about currents the past few days, so today we are going to do a lab involving this topic. What we want to find out is how current is related to voltage and resistance. Before we start though, I want to mention a few things to you as a group. I have divided you into pairs so you will be working with a partner today. The groups are listed on the board:
Group #1 Group #2
Kevin John
Carl Steven
All the necessary equipment for this lab is located at the front desk. One thing to remember though is that this equipment is expensive, so please be careful when you are working with it. If the resistor gets warm or hot, you are running too much current through it. Check for this every once in a while.
Now remember that we are looking for a relationship between current, voltage, and resistance. If you have trouble getting started, think back to the activity we did last week with the magnets. What was the process we used to determine that the rings were in fact magnets? Could you apply this technique to this lab? It might be a good idea to do some brainstorming during this lab, but it is entirely up to you as to how you want to go about reaching a conclusion.
Activity: Pass out the equipment and help set up if there are questions.
* If this were a high school class, I would show the students how to set up the equipment and leave one set up for reference.
Ask the groups for a game plan that they will follow.
Ask the groups to check with me before starting so that I may give specific group instructions.
Group #1 ( Hold voltage constant.
Group #2 ( Hold current constant.
Mention accessibility to the computer, if it is desired.
Conclusion: As a group discuss the conclusion that was reached during this lab.
What is the relationship?
V = IR
Is there a constant in this equation? How can we find it?
Items to watch for:
Definite, clear introduction to the lesson.
State clear conclusions reached from the lesson. Make sure to summarize, even if short on time.
Objective: To use cooperative learning as a tool to solve a circuit puzzle.
Instructions:
1. Work together as one group.
2. Assign tasks within the group. For example, maybe assign one member as "leader," one as "interpreter," and one as "representative."
3. Make a list of steps taken to reach a conclusion. Include the name of the member responsible for each step.
4. Once a conclusion is reached, be certain that each member fully understands the procedure and the results. I will randomly select one student to explain the results and the process used.
Grading Assessments:
1. A list explaining the processes used and the distribution of work among group members will be turned in for a portion of the final grade.
2. The presentation of the process and results will count for a portion of the final grade.
3. An evaluation of your group members' contribution to the project will be turned in for a portion of the final grade.
Group Member Evaluation
Your name:
Group member being evaluated:
Least Most
Contribution of development of plan. 1 2 3 4
Responsibility of role. 1 2 3 4
Participation in thought process. 1 2 3 4
Willingness to cooperate. 1 2 3 4
VII. DEMONSTRATIONS
A. Encouraging Energy Saving with a Clamp-On Ammeter
1. Current
2. Calculating the energy used by a given appliance requires a measurement of the ac current needed to operate it. Three load-current ranges are provided: 0.3-6.0A, 3.0-60A, and 30-600A. A line splitter is included to allow the clamp-on ammeter to be clamped around one leg of the load circuit. See Figure 1.
Figure 1
3. Lawrence, R. (1994). Encouraging energy saving with a clamp-on ammeter. The Physics Teacher, 32, 510-511.
B. A Model of Potential Difference in a Simple Electric Circuit
1. Voltage
2. This describes how potential difference plays a role in electric circuits.
3. Turley, M. (1994). A model of potential difference in a simple electric circuit. Australian Science Teacher Journal, 40, 60-61.
C. Trick of the Trade: A Series-Parallel Demonstration
1. Resistance
2. Using parallel resistors, the students are shown that it possible for a 40-Watt light bulb to burn brighter than a 100-Watt light bulb connected in the same circuit. See Figure 2.
3. Steiger, W., & Hwang, S.R. (1995). Trick of the trade: a series-parallel demonstration. The Physics Teacher, 33, 590.
Figure 2
D. Trick of the Trade: A Colorful Current Event
1. Induced current
2. A toy dc electric motor is connected to a galvanometer. The shaft is turned by hand to demonstrate the induced current. Reversing the direction of the spin on the shaft reverses the direction of the induced current.
3. Gore, R.G. (1994) A colorful current event. The Physics Teacher, 32, 375.
E. Tinkering with Gauss's Law
1. Electric field
2. A balloon is filled with iron fillings and then inflated. Vectors are made using a Tinkertoy stick with a small magnet glued to one end and an arrowhead affixed to the other. These can then be used to demonstrate spatial aspects of Gauss's Law.
3. Brueningsen, C. (1994) Tinkering with Gauss's law. The Physics Teacher, 32, 12-13.
F. Building a Magnetic Levitation Toy
1. Magnetism
2. This demonstrates a great method that can be used by teachers or students to explain the interaction of two dipoles.
3. Kagan, D. (1993) Building a magnetic levitation toy. The Physics Teacher, 31, 432-433.
G. Multi-Loop Circuit Problems
1. Multi-loop circuits
2. This method demonstrates to students the immediate changes that occur when loops must be resolved. This demonstration is performed on a spreadsheet, such as Excel. See Figure 3.
3. Hart, F.X. (1995) Solving multi-loop circuit problems with a spreadsheet. The Physics Teacher, 33, 542.
Figure 3
H. Get the LED Out
1. Electrical concepts
2. Demonstrates the difference between ac and dc power sources. Two light- emitting diodes are connected to power sources, one ac and one dc. When twirled in a circle on the ends of cable, the differences between the two can be observed.
3. Jewett, J.W. (1991) Get the led out. The Physics Teacher, 29, 530-534.
I. Magnetic Rings on a Glass Rod
1. Magnetism
2. Demonstrates the concept of magnetic rings and polarity by levitating magnetic rings (repulsion) on a glass rod.
J. Twin Rings
1. Current
2. The idea of current in a magnet field is demonstrated.
VIII. LABORATORY ACTIVITIES
A. Black Box Circuit puzzle
1. Parallel and/or series resistors.
2. The student must measure the resistance between four different connectors in a closed box. See Figure 4.
Figure 4
Using this information, the student must then show how the resistors are arranged inside the box. Shown below is a good schemata to help the student get started. See Figure 5.
Figure 5
B. Overcoming Resistance with Fractals. A New Way to Teach Elementary Circuits.
1. Circuits
2. This experiment requires the student to construct a Sierpinski gasket from resistors and measure its resistance as a function of size. In a group of three, each student wires nine resistors to form the first generation of the gasket. A second generation gasket can then be formed by wiring the products together, and so on. The vertex-to-vertex resistance is measured by an ohmmeter. Data is entered into a spreadsheet and generated on log-log plot of resistance along the outer leg of the network. See Figure 6 (a), (b), and (c).
3. Ching, W.K. (1994) Overcoming resistance with fractals. A new way to teach elementary circuits. The Physics Teacher, 32, 546-551.
Figure 6
C. Resistance of a Wire as a Function of Temperature.
1. Resistance
2. The student discovers a linear relationship between temperature and resistance. The temperature coefficient of resistance is easily calculated from the slope of the graph and can be compared with standard values. See Figure 7.
3. Henry, D. (1995) Resistance of a wire as a function of temperature. The Physics Teacher, 33, 96-97.
Figure 7
IX. SAFETY CONSIDERATIONS
A. The principal is responsible for all of the teachers, students, and
faculty members in the school. Their main responsibility is to ensure that the teachers are doing their job properly and are capable of handling a situation should one arise.
The science department chairman is responsible for overseeing all of the science teachers in his/her department. This means that he/she handles all immediate problems that can be dealt with before it is brought to the principal.
The science teacher is responsible for the safety and well-being of all of his/her students. This includes providing a good working environment that is ideal for learning. Specifically for science teachers, this also includes safety in the laboratory. Every precaution should be taken to ensure that the students are not hurt. This includes safety warnings, rules, and regulations.
B. Some of the dangers associated with this unit are electrical shock, and a slight chance of burning. These may be encountered during laboratory exercises. To avoid these dangers, the students will be well advised before beginning an activity. The area where the student is working will be dry and liquids will not be allowed any of the equipment. Also the amounts of current and voltage will be kept to a minimum to reduce the chance of harm to the student.
C. The first activity that may include a danger is the twin rings. When the ring is allowed to levitate over a period of time, it begins to get warm and eventually may burn a student. Tape will be placed around the ring to allow the student a form of protection. Also, the apparatus will be left on for a long period of time.
Another precaution that must be taken will occur during the derivation of Ohm's Law. Resistors will be used along with current and voltage. If too much current flows through the resistor, it will get warm. The students will be told this ahead of time so that they may regulate their amounts. Also, a given amount will be suggested to the student so that they will not receive any shocks.
If any of these situations get out of control, the real damage will be to the equipment. The students should not experience any type of unpleasantness from performing these experiments. However, if a student displays blatant carelessness their grade will be affected by this behavior.
X. SPECIAL STUDENT NEEDS
A. One physical disability that I chose to deal with in this section of the unit plan was paraplegia.
B. Some handicaps that the student may encounter in the physics classroom include difficult in moving around the laboratory and accessibility to lab countertops. These handicaps are more of a matter of inconvenience than they are preventative in allowing the student to learn. The effect of not accommodating to this student's needs may make the student feel uncomfortable.
C. Accommodations for this student would be relatively easy. Classroom activities would not necessarily need to be altered in any form for this student. The biggest accommodation would be in the lab. This matter could be solved by finding a work station that was more suitable for the student. Also, all aisles and passageways should remain clear, but this is a part of lab procedure anyway.
D There are many possible enrichment activities that a gifted student might perform. One in particular might be for the student to pick a topic and then devise a lab for that topic. An example may be one the activities suggested by Arons in a previous section (IV-B). A long term project which proves that electrons exist as free entities in metals may be one such topic. The student would then be responsible for all aspects of this lab, including the approach, gathering of data, interpretation, and presentation of conclusions.
XI. RESOURCES
Bowker, R.R. (1996). El-hi textbooks & serials in print. New Providence, NJ: Reed Reference.
A. See the appendix for a copy of the title page and physics section. I chose the textbook that I did for various reasons. It supplied a strong background on famous scientists. There were also many activities for the students to obtain practice. The text was written in a manner that I felt the students would be able to understand. I also saw different opportunities in which the student could interact with the text by writing questions and forming diagrams.
B. It appeared that much of the equipment necessary to conduct many of the labs and demonstrations were readily available. However, the initial cost of purchasing this equipment may be high if it is not already in stock. The price listed below was obtained from a variety of supplier catalogs. This does not include every item that would be required to perform every lab and/or demonstration, but it does include those items which are necessary for a majority of them.
Item Supplier Price
Ac/Dc Ammeter Cenco 1996 $19.95
Voltmeter Cenco 1996 $110.10
Digital Multimeter Cenco 1996 $49.95
Frey ë94-í95 $56.00
Fischer ë96-í97 $69.00
Resistors Cenco 1996 $8.00
Frey ë94-í95 $2.25
Fischer ë96-í97 $9.75
Mounted Resistors Frey ë94-í95 $29.19
Wire Leads Frey ë94-í95 $6.95
Knife Switches Frey ë94-í95 $2.95
Porcelain Lamp Sockets Frey ë94-í95 $2.15
XII. STUDENT ASSESSMENT
A. Process skill assessment ( Students will be assessed on a variety of skills in the laboratory. Precision in measurement, data, and results will be considered and counted with equal amount to the accuracy of the results. This information will be turned in with the final lab report. Also to be considered in the assessment of grades is the accumulation of data gathering, formation of a hypothesis, experimentation, interpretation of the data and the final explanation of the experiment. Students will answer questions such as "What do you predict will be the outcome in this situation?" and "What does this graph represent?"
B. Scientific disposition assessment ( An alternative assessment of a student's disposition is probably best done through a cooperative learning activity. Through this method, a student's peers can assess the student on different aspects of the assignment. Some of these aspects include knowledge of the scientific process, willingness to cooperate on the assignment, and participation in the thought process. Students will answer questions such as "What could you do to improve the results?", "Is it possible to reach another conclusion?" and "How might you change the application of this principle?"
XIII. CONGRUENCE WITH STATE AND NATIONAL GOALS
A. This unit plan aligns with the Illinois State Goals for Learning to a high degree. This is demonstrated in the following areas:
1. The concepts and basic vocabulary of physical science and their application to life and work in contemporary technological society will be addressed when the unit is introduced through a concept change lesson.
2. The social and environmental implications and limitations of technological development will be addressed during the discussion of circuits in the household.
3. The principles of scientific research and their application in simple research projects will be introduced during classroom demonstration and executed during the circuit puzzle lab.
4. The processes, techniques, methods, equipment, and available technology of science will be created mostly by the students. The equipment will be provided, but the students must develop a method to reach a conclusion.
B. This unit plan aligns closely with the goals for teaching enunciated by the National Science Education Standards. This is demonstrated in the following areas:
1. Inquiry-based instruction will be incorporated when Ohm's Law is introduced. The students will have the opportunity to derive the relationship from experimentation. They must then interpret their data to form the equation V = IR.
2. Guidance and facilitation of student learning for all students will be available at all times from either their peers as a form of cooperative learning or from the outside references. I will also be considered as a source.
3. Ongoing assessment of teaching and student learning will be monitored through continuous quizzes, labs, reports, and exams.
4. Time, space, and resources needed for learning science will be available to the students to the best of my ability. Time will be allotted for a project at my discretion, and will be maximized during each period.
5. The creation of learning communities that reflect the intellectual rigor of scientific inquiry and the attitudes and social values conducive to science learning will be encouraged to students through an opportunity for some extra credit points.
C. This unit plan aligns closely with Project 2061's Benchmarks for Science Literacy. A large part of this unit is to incorporate the correct procedures used with the scientific process. The student will be forced to use this process during non-instructed labs. The section that is most closely related to this unit plan is concerned with motion. Benchmarks suggests that at grades 9- 12, the student should be aware that charges produce electromagnetic waves. This is included in lecture demonstrations throughout this unit. This allows the student to fully understand the material and be able to apply it to other situations, whether they are in the classroom or real world.
XIV. REFERENCES
Arons, A.B. (1990). A guide to introductory physics teaching. New York,
NY: John Wiley & Sons.
Bowker, R.R. (1996). El-hi textbooks & serials in print. New Providence,
NJ: Reed Reference.
Brueningsen, C. (1994) Tinkering with Gauss's law. The Physics Teacher,
33, 12-13.
Ching, W.K. (1994) Overcoming resistance with fractals. A new way to teach
elementary circuits. The Physics Teacher, 32, 546-551.
Gore, R.G. (1994) A colorful current event. The Physics Teacher, 32, 375.
Hart, F.X. (1995) Solving multi-loop circuit problems with a spreadsheet. The Physics Teacher, 33, 542.
Henry, D. (1995) Resistance of a wire as a function of temperature. The Physics Teacher, 33, 96-97.
Jewett, J.W. (1991) Get the led out. The Physics Teacher, 29, 530-534.
Kagan, D. (1993) Building a magnetic levitation toy. The Physics Teacher, 31, 432-433.
Lawrence, R. (1994). Encouraging energy saving with a clamp-on ammeter. The Physics Teacher, 32, 510-511.
Steiger, W., & Hwang, S.R. (1995). Trick of the trade: a series-parallel demonstration. The Physics Teacher, 33, 590.
Turley, M. (1994). A model of potential difference in a simple electric circuit. Australian Science Teacher Journal, 40, 60-61.
Wida, S. (1992) Neodymium magnets. Science Teacher, 59, 28-31.