Download Applications of series and parallel circuits

EDSE 732 SECONDARY SCIENCE METHODS
4/17/10
Lesson Plan – Cooperative Learning
Moritz Huegle
1. Topic of the lesson
Applications of series and parallel electrical circuits
This lesson will focus on the knowledge about parallel and series circuits gained in the
lesson before. The students will review the relationship between currency, voltage and
resistance in complex circuits and learn about applications such as the current and voltage
divider.
2. Class
The lesson plan is taken from a unit about the concept of the electrical resistance in physics.
It is designed for an eleventh grade physics classroom. The students are familiar with the
basic concepts about electricity, complex circuits and have profound knowledge about the
mathematical techniques such as proportionality and anti-proportionality that will be used
during the lesson.
3. Standards
The students will be measuring current, voltage and resistance in series and parallel
electrical circuits with an analog and digital multimeter in order to record the information.
(Standards P-1.3 and P-4.4)
Working with voltage sources and the components of electrical circuits it is important for the
students to develop an understanding of how to work with electric instruments safely.
(Standard P-1.2)
Organization and interpretation of the collected data using tables, models and formulas will
be important in order to calculate the quantities of current and voltage in the overall circuits
and different branches using Ohm's law. (Standards P-1.5 and P-4.5)
In addition to that the students will present their results to their groups and or the class.
They will have to defend their conclusion talking about advantages and disadvantages
(Standard P-1.9)
1/14
EDSE 732 SECONDARY SCIENCE METHODS
4/17/10
Lesson Plan – Cooperative Learning
Moritz Huegle
4. Objectives
•
Students should be able to calculate electrical resistances, currents and voltages in
the circuits using Ohm's law.
•
Students should be able to apply their knowledge about parallel and series circuits to
more complex circuits that include branches of both kinds of circuits.
•
Students should be able to use scientific apparatuses safely.
•
Students should be able to set up, execute experiments and draw schematic circuit
diagrams of complex circuits
•
Students should be able to analyze, evaluate and interpret the data afterwards.
•
Students should be able to present their results on a transparency in class
•
Students should be able to communicate their knowledge and understanding of
circuits with their partners, groups and the class.
•
Students should be able to develop further social competences. They see the
importance of individual effort during group work and respect each other’s results.
They also engage actively in classroom discussions.
5. Context
The present unit is about the electrical resistance. Its definition was introduced in the first
lesson: R:=U/I (U is the voltage, I the current and R is the resistance)
Characteristics of different conductors and resistors have been recorded in student-focused
experiments using simple circuits. The students have become familiar with the use of
measuring devices such as volt- and ampere-meter and have used them throughout the
unit.
The relevance and importance of the subject of this unit has been pointed out talking about
energy factors of light bulbs and everyday examples such as the Christmas light set.
The previous lesson supplied the students with the general knowledge about parallel and
series circuits. Today’s lesson will address this knowledge and will focus on the discussion
of voltage and current dividers in different circuits.
Including the these two very important tools in different circuits will deepen the students
knowledge and help them to understand the implementation of the physics they learn in
school into their life’s. Voltage and current dividers are used in dimmers and many other
electronic devices.
The students will learn how gather certain information out of given material, present it to
2/14
EDSE 732 SECONDARY SCIENCE METHODS
4/17/10
Lesson Plan – Cooperative Learning
Moritz Huegle
their peers and apply in a more complex circuit. They will see that knowing about a small
number of laws and models provides them with enough information to solve very complex
problems if only they address the problems in a structured an organized way.
To achieve the goal they need to work together in groups with everyone being accountable
for the group results. They will share their knowledge with their partner and listen to his or
her knowledge in order to complete the task.
This way of addressing a physical subject focuses on more than just the physical data and
results. The students learn to work together in teams, each one working on one specific part
of the problem and then after bringing it all together finish the task together.
This social component is important in order to develop scientific activity and understanding.
Presenting and defending their own work is another important aspect of scientific research
and will -together with the above mentioned aspects- enable the students to engage actively
in teamwork in and outside of science.
The scientific aspect is still very important and by the end of the unit the students will be
able to apply their knowledge not only to actively engage in global issues such as energy
saving but also to their everyday life which includes devices such as dynamos on bikes,
dimmable lamps. The knowledge about voltage and current dividers will enable them to use
electrical devices more safely now knowing how to divide currents and voltages into smaller
portions.
6. Materials
Items per group
-
Voltage source or a sufficient amount of batteries (6V)
-
a few wires or electronic snapkits with resistors and sockets for the batteries
-
resistors different quantities (at least 40 and 80Ω) and a potentiometer
-
diode
-
a volt- and ampere-meter or a multimeter (analog or digital)
-
transparencies and pen or big sheets of paper and markers
Items per student
-
worksheet with two problems (addendum 1)
-
Handout for the assessment center (addendum 2)
-
Material for the different components (addendum 3-5)
3/14
EDSE 732 SECONDARY SCIENCE METHODS
4/17/10
Lesson Plan – Cooperative Learning
Moritz Huegle
7. Instructional Sequence
Time
in
Min
Section
Methods
media
Planned process and activities
.
10
Introduction
Teacher (T) picks up the subject of the last lesson up
Frontal
“Recapitulate the last lesson and the homework. Write
impulse
down any question you have but also be prepared to
answer questions”
T explains the carousel method
-
Students (S) are numbered off with 1 and 2 (so that
Frontal
half the class is 1and half the class is 2)
instruction
-
S with number 1 build a circle face outwards
-
S with number 2 build a circle around the inner
circle (face inwards) each matching up with a
partner from the inside
-
Inner circle take the role of the teacher, outer circle
that of the student asking questions
-
After 5 minutes outer circles rotates 2 students to
the right and roles are changes
10
Review and
Students ask the ‘teacher-students’ questions, ‘teachers’
Recapitulation
try to answer.
Carousel
After the change of roles the former ‘teachers’ have the
chance to ask further unanswered questions and the
former students have the chance to test their
understanding trying to answer the questions
10
Review
S get two problems to work on for 5 minutes (see
Think-
addendum 1)
15
S share their results with partner for 5 minutes
Pair-Share
Collection and
Teacher collects students’ results at the blackboard and
Teacher
confirmation
goes over unanswered questions together with the class
guided
Blackboard
4/14
EDSE 732 SECONDARY SCIENCE METHODS
4/17/10
Lesson Plan – Cooperative Learning
Moritz Huegle
5
Stating the
problem
T introduces the problem:
“Browder Electronics Co Inc down on Wayne Street is
hiring new employers and you all were invited for an
assessment center. You will be working on a project in
groups of three. The project can be divided in three major
Impulse
Frontal
instructions
components and each of you will be responsible for one of
the three. The company wants to find out more about your
individual skills but also about your ability to work in
different groups. You will therefore be put in groups of four
working on one of the components. After that you will get
back to your initial group and explain your component to
them since you all should know everything about the
project. You will then put the components together and
present your results to the jury. Each of you should be
able to present your final project next lesson and should
be prepared to defend it.”
The problem with instructions will be distributed to the
students and introduced by the teacher
(problem see addendum 2)
40
Laboratory
OHP or
Powerpoint
Slide
Students in the home groups make sure they understand
Jigsaw
what they have to do and then get together in the expert
Home group
groups of four.
work
The expert groups work on the material and do some
experiments about the component they are dealing with
It is important that they know how their component works,
Expert group
and how it might be used in the circuit.
work
(materials for the components see addendum 3-5)
The home groups get back together and explain each
other the function and the mode of operation of their
component.
Home group
Groups come up with a circuit that satisfies the requests
work
by putting the current and voltage divider as well as the
5/14
EDSE 732 SECONDARY SCIENCE METHODS
4/17/10
Lesson Plan – Cooperative Learning
Moritz Huegle
potentiometer in the right spots in the circuit.
S verify their results measuring the important quantities in
their circuits.
The students will present their work in the next lesson
giving each group enough time to present and defend their
results and to answer questions
8. Assessment
In the beginning the students will be asked to review the material of the previous lesson and
to think of any questions they still have about parallel and series circuits and the specific
relationship. They should also be prepared to answer questions about the content.
During the carousel the half of the students will take the role of a student asking questions
and the other half will take the role of the teacher trying to answer the questions. After a few
minutes the carousel ‘moves’ and the roles change. This is the chance to ask unanswered
questions and to see how good one’s understanding of the subject is.
The students will then be given two problems; one about a series circuit and one about a
parallel circuit. Everyone gets 5 minutes to think about and to solve the problem. After that
the students share their results with a partner. The final solution will then be written down on
the board. Any unanswered questions about the subject related to the general conceptions
of series and parallel circuits will be address in class at this point.
The detailed review of the content is to secure a profound base for the following jigsaw and
is also a preparation for the quiz the students will be given at the beginning of the next
lesson.
The jigsaw includes experiments measuring voltage and current in circuits. The experiments
main purposes are to collect the data that can be used to conclude the general formula of a
voltage or current divider and to come up with possible solutions for the main problem. The
material for the expert groups includes questions and assignments that will guide the
student through the activity helping them to understand the subject matter.
The presentation of the results will take place in the next lesson.
6/14
EDSE 732 SECONDARY SCIENCE METHODS
4/17/10
Lesson Plan – Cooperative Learning
Moritz Huegle
9. References
National Science Education Standards (1996)
Retrieved August 23, 2009, from The National Academies Press
Web Site: http://www.nap.edu/openbook.php?record_id=4962
South Carolina Curriculum Standards (2005)
Retrieved August 23, 2009, from South Carolina Department of Education
Web Site: http://ed.sc.gov/agency/Standards-and-
Learning/AcademicStandards/old/cso/standards/science/
All About Circuits. (n.d.) Retrieved September 30, 2009 from
http://www.allaboutcircuits.com
10. Addendum
10.1. Worksheet
7/14
EDSE 732 SECONDARY SCIENCE METHODS
4/17/10
Lesson Plan – Cooperative Learning
Moritz Huegle
10.2 Assignment for the jigsaw
Browder Electronics Co Inc Assessment Center
You are given a 6V battery, two resistors, a potentiometer and a diode.The diode holds only
2V and the current through the diode should be variable from 0 to 50mA.
The three major components of your circuit will be a voltage divider, a current divider and
a potentiometer.
The purpose of the expert groups is to go through the material for one of the components.
You will be given some background information that will allow you understand the principle
and if necessary to develop a formula. You will then be asked to collect data in an
experiment to verify your formula and to understand how to implement the component in a
circuit.
You will present your findings to your home group and you and your partners will then work
on putting the requested circuit together:
1. Discuss how to put the three components together in one circuit
2. Draw a schematic circuit diagram.
3. Calculate the quantity of the two resistors in your circuit
4. Put the circuits together using the material that was given to you
5. Verify your results measuring the important voltages and currents using the
potentiometer to vary the current through the diode.
6. Make sure everyone in your group understands the circuit and can present and
explain the major components.
7. Prepare a transparency to help you present your results
8/14
EDSE 732 SECONDARY SCIENCE METHODS
4/17/10
Lesson Plan – Cooperative Learning
Moritz Huegle
10.3 Material for the expert group ‘voltage divider’
The voltage divider
The schematic diagram above depicts the simplest two resistor voltage divider. It includes
two resistors R1 and R2 in a series circuit.
Build a series circuit with any two resistors and a battery with Uin=6V.
Measure current and voltage at the important points in the circuit and fill in the blanks in the
following table.
Voltage U in V
Current I in A
Resistance R in Ω
R1
R2
Rtotal
6V
Verify your results by calculating the quantities with Ohm’s law:
Voltage U in V
Current I in A
Resistance R in Ω
R1
R2
Rtotal
6V
Explain possible offsets between your measurements and calculations.
__________________________________________________
9/14
EDSE 732 SECONDARY SCIENCE METHODS
4/17/10
Lesson Plan – Cooperative Learning
Moritz Huegle
__________________________________________________
__________________________________________________
Now look at the relationship of the voltage drop and the resistance. What do you notice?
Hint: If you don’t see any connection yet calculate the ration of the two resistors and
compare it with the ratio of the voltage drops.
__________________________________________________
__________________________________________________
Imagine you have two unknown resistors R1 and R2 what is the formula for the voltage Uout if
your initial voltage is Uin? (Use Ohm’s law and the knowledge gained in the experiment
above)
This result supplies us with a very important tool and explains the name voltage divider. It
refers to the fact that we can partition a voltage among components in a circuit. Using two or
more resistors in a series circuits allows us to divide the voltage at each resistor into
portions we can control with the choice of the resistors.
We can use it to supply a second circuit with a different voltage than that of an available
battery or power supply. The larger the resistor the larger is the voltage drop over the
resistor.
Hint:
When you are back in your home group apply the knowledge about the voltage divider to the
requested voltages.The knowledge about the voltage and the maximum current allows you
to calculate the total resistance.
10/14
EDSE 732 SECONDARY SCIENCE METHODS
4/17/10
Lesson Plan – Cooperative Learning
Moritz Huegle
10.4 Material for the expert group ‘current divider’
The current divider
The
schematic
diagram above
depicts the simplest two resistor current divider. It includes two resistors R1 and R2 in a
parallel circuit.
Build a parallel circuit with any two resistors and a battery with Uin=6V.
Measure current and voltage at the important points in the circuit and fill in the blanks in the
following table.
Voltage U in V
Current I in A
Resistance R in Ω
R1
R2
Rtotal
6V
Verify your results by calculating the quantities with Ohm’s law:
Voltage U in V
Current I in A
Resistance R in Ω
R1
R2
Rtotal
6V
Explain possible offsets between your measurements and calculations.
__________________________________________________
__________________________________________________
_________________________________________________
11/14
EDSE 732 SECONDARY SCIENCE METHODS
4/17/10
Lesson Plan – Cooperative Learning
Moritz Huegle
Now look at the relationship of the current going through a resistor and the resistor. What do
you notice?
Hint: If you don’t see any connection yet try to fill in the blank in the following sentence and
calculate the ration of the two resistors and compare it with the ratio of the branch currents.
(The greater the resistance the ____________ the current)
__________________________________________________
__________________________________________________
Imagine you have two unknown resistors R1 and R2 what is the formula for the voltage I1 if
your initial current is Iin? (Use Ohm’s law and the knowledge gained in the experiment
above)
This result supplies us with a very important tool and explains the name current divider. It
refers to the fact that we can partition a current among components in a circuit. Using two or
more resistors in a parallel circuit allows us to divide the current at each resistor into portions
we can control with the choice of the resistors.
We can use it to supply a second circuit with a different current than that of an available
battery or power supply. The larger the resistor the smaller is the current through the
resistor.
Hint:
When you are back in your home group apply the knowledge about the current divider to
the variable current. You need to implement the potentiometer into your current divider.
12/14
EDSE 732 SECONDARY SCIENCE METHODS
4/17/10
Lesson Plan – Cooperative Learning
Moritz Huegle
10.5 Material for the expert group ‘potentiometer’
The potentiometer
A potentiometer is a resistor that can
be adjusted.
The easiest set-up of a potentiometer
is a long piece of wire or pencil
“lead”connected to a battery.
Adjusting the position of one of the
connection to the
multimeter changes the resistance.
The principle of the potentiometer is
based on three different ‘terminals’ (wires). One is connected to a battery, a second one is
connected to ground (no voltage or resistance) and the third is variable on a resistive
material, which has a low resistance at one end with an increasing resistance towards the
other end. The position of this wire can be changed and thus the resistance is changed.
Changing the resistance one can control the current running through a circuit.
Build the circuit as shown above and measure the resistance at more than 2 positions
verifying the variable resistance.
Position
1
2
3
4
Resistance
Determine the range of your ‘potentiometer’: _____________________________________
You are given a potentiometer that can be adjusted from 0 to 10kΩ. Verify the range of the
potentiometer using your multimeter and try the different positions of the potentiometer
making yourself familiar with the configuration.
Now build a series circuit with a resistor (R1=100Ω), the potentiometer and a 6V battery.
Measure the current and voltage in the circuit as you change the resistance of the
potentiometer.
Potentiometer-resistance in
Ω
13/14
EDSE 732 SECONDARY SCIENCE METHODS
4/17/10
Lesson Plan – Cooperative Learning
Moritz Huegle
Total resistance in Ω
Total current in A
Total voltage in V
What is the relationship between the resistance of the potentiometer and the current in the
circuit?
Now put the resistor, the potentiometer and the 6V battery in a parallel circuit. Measure the
current and voltage in the circuit and in the different branches as you again change the
resistance of the potentiometer.
Potentiometer-resistance in Ω
Total resistance in Ω
Total voltage in V
Total current in A
Resistor current in A
Potentiometer current in A
What is the relationship between the resistance of the potentiometer and the current through
the potentiometer?
Hint:
When you are back in your home-group apply your knowledge about the potentiometer and
how it works in the two circuits to the fix current you have running through the main circuit
which is supplied by a 6V battery.
14/14