Vfp 2 -1-

EET - EM-7 VFP-2
DC Circuit Analysis (Kirchhoff’s Voltage Law) 1
VFP-2 – Lesson Preparation
o Topic : Kirchhoff's voltage laws
o Date and Time : Monday 20/ 10 / 2014 8:00 am
Mohammed Omar 104

EET - EM-7 VFP-2
Table of Content
1. Didactic Reflection.....................................................................................................................................................3
1.1 Curriculum Analysis:........................................................................................................................3
1.1.1 Module Description:..................................................................................................................................3
1.1.2 General objective of the module:............................................................................................................4
1.1.3 Specific Objectives of module units: ......................................................................................................4
1.2 Content Analysis .............................................................................................................................5
1.2.1 First Kirchhoff's Voltage Law description ......................................................................................5
1.2.2 RCT Kirchhoff's Voltage Law description..............................................................................................8
1.2.3 The lesson Content description of Kirchhoff’s Voltage Law ............................................................10
1.3 Didactic Analysis ...........................................................................................................................12
1.3.1 The environment .....................................................................................................................................12
1.3.2 Methods and Tools .................................................................................................................................13
2. Lesson Plan ..............................................................................................................................................................15
2.1 Learning Objectives.......................................................................................................................15
2.2 Overview of the Intended Process.................................................................................................16
3. Bibliography.............................................................................................................................................................18

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1. Didactic Reflection
1.1 Curriculum Analysis:
The module name is Electrical Circuits-1 and its code is (ELT 106). The contact hours of
this module are 3 hours theory and tutorial per week without practical and its credit hours
are 3.
1.1.1 Module Description:
This module is taught in electrical department for first trimester and contains on six units:
Fundamentals of electrostatics
Batteries
Principles of DC circuits
DC circuits analysis
Electromagnetism
Magnetic circuits
In addition, explanation of electrostatics laws, batteries, DC circuit analysis,
electromagnetism and magnetic circuits. The course also include: capacitors, Ohm's law,
Kirchhoff's laws, series and parallel circuits, power, and DC bridges.
The topic of this lesson is Kirchhoff's voltage law and it is belonged to DC circuit analysis
unit. Before this units the trainees study two units are
Fundamentals of electrostatics
Batteries

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When they finished studying these two units they will come to DC circuit analysis unit.
under this unit there are five topics are:
 Methods of DC circuit analysis.
 Kirchhoff's current and voltage laws.
 Mesh current method.
 Node voltage method.
 Superposition method.
1.1.2 General objective of the module:
The module is designed to give the trainees basic knowledge of electrostatic, batteries, and
fundamentals of DC current. Also covers DC circuits analysis, electromagnetism, and
magnetic circuits.
1.1.3 Specific Objectives of module units:
When the trainees finish each module units they will get some skills related to the unit so at
the end of trimester they have to be able to
 Explain the basic electrostatics terms.
 Describe the types of capacitors
 Determine the total capacitance for different capacitor connections.
 Describe the types of batteries and their constructions and connections.
 Explain the different resistor connections and calculate the total resistance.
 Explain and apply Ohm's law.
 Represent Ohm's law graphically.
 Apply Kickoff’s laws, and voltage and current division rules
 Solve simple DC circuits.
 Explain the principles of electromagnetism.
 Solve simple magnetic circuits.
.

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1.2 Content Analysis
Kirchhoff's Voltage Law topic one of the most important topic in electrical department that
related to series circuits so there are different types of defining and explaining its steps in
the colleges..
1.2.1 First Kirchhoff's Voltage Law description
The following description of Kirchhoff's Voltage Law from firs research source is written by
Tony R. Kuphaldt under the Design Science License. (Kuphaldt, 2002)
This principle is known as Kirchhoff's Voltage Law (discovered in 1847 by Gustav R.
Kirchhoff, a German physicist), and it can be stated as such:
"The algebraic sum of all voltages in a loop must equal zero"
Let's take a look at our example series circuit, this time numbering the points in the circuit
for voltage reference:
Fig. 1.2.1
(Kuphaldt, 2002)
Series Circuit
If we connect a voltmeter between points 2 and 1, red test lead to point 2 and black test
lead to point 1, the meter would register +45 volts. Typically the "+" sign is not shown, but
rather implied, for positive readings in digital meter displays. However, for this lesson the
polarity of the voltage reading is very important and so I will show positive numbers
explicitly:
E2-1 = +45 V

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When a voltage is specified with a double subscript (the characters "2-1" in the notation
"E2-1"), it means the voltage at the first point (2) as measured in reference to the second
point (1). A voltage specified as "Ecd" would mean the voltage as indicated by a digital
meter with the red test lead on point "c" and the black test lead on point "d": the voltage at
"c" in reference to "d".
Fig. 1.2.2
(Kuphaldt, 2002)
voltmeter
If we were to take that same voltmeter and measure the voltage drop across each resistor,
stepping around the circuit in a clockwise direction with the red test lead of our meter on
the point ahead and the black test lead on the point behind, we would obtain the following
readings:
E3-2 = -10 V
E4-3 = -20 V
E1-4 = -15 V

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Fig. 1.2.3
(Kuphaldt, 2002)
voltages measurements
We should already be familiar with the general principle for series circuits stating that
individual voltage drops add up to the total applied voltage, but measuring voltage drops in
this manner and paying attention to the polarity (mathematical sign) of the readings reveals
another facet of this principle: that the voltages measured as such all add up to zero:
E2-1 = +45 V
E3-2 = -10 V
E4-3 = -20 V
÷ E1-4 = -15 V
0 V

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1.2.2 RCT Kirchhoff's Voltage Law description
The second explanation of Kirchhoff’s Voltage Law is written by Edvard Csanyfor
University of Liverpool. This content description is same RCT content. (Kirchhoff’s Laws,
2000)
The Kirchhoff’s Voltage Law, states that:
The algebraic sum of voltages around a closed circuit loop is zero.
There’s the phrase ‘algebraic sum’ again, so we must recognize that the direction of
voltages matters when using Kirchhoff’s Voltage Law.
Fig. 1.2.4
(Kirchhoff’s Laws, 2000)
circuit loop
Fig. 1.2.4 shows a circuit loop, which is part of a larger circuit. The loop involves four
nodes, ABCD, between which are connected four components. In this case the four
components are resistances, but Kirchhoff’s Voltage Law can be applied no matter what
components are connected in the closed circuit loop. The voltages across the four
resistances comprising the circuit loop have been defined as V1, V2, V3, V4 and
Kirchhoff’s Voltage Law allows us to write down an equation relating these voltages. If we
think about travelling around the closed circuit loop in any direction, we note that the four
voltages will be encountered in sequence.

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Two of the voltage arrows will point in the direction of travel and two will oppose the
travel. The algebraic sum of voltages needs to take account of this difference in relative
direction.
To apply Kirchhoff’s Voltage Law correctly, we must make arbitrary choices about the
direction of travel around the closed circuit loop and the contribution which the separate
voltages make to the algebraic sum around the closed circuit loop. Suppose we travel
around the loop in the clockwise direction (ABCD) and that voltages opposite to the
direction of travel make a positive contribution to the algebraic sum. In travelling from A to
B the voltage V1 is encountered and it is in a direction which is opposite to the travel.
sum. Expressed mathematically, the algebraic sum of voltages around the closed loop
ABCD is: + V1 + V2 – V3 – V4 and Kirchhoff’s Voltage Law states that this sum is equal to
zero:
+ V1 + V2 – V3 – V4 = 0 (2.4)
The other two combinations are:
Clockwise around the loop (ABCD), with the arrow positive:
- V1 – V2 + V3 + V4 = 0 (2.5)
Anticlockwise around the loop (ADCB), against the arrow positive:
- V1 – V2 + V3 + V4 = 0 (2.6)

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If we go through these two these descriptions we will not see much different but there are two
main different
Table 1.2.1
First Content Description Second Content Description (RCT)
The direction of resistor voltage is same with
its current which is flow through it.
The direction of resistor voltage is opposite
with its current which is flow through it.
.The source current goes from minus to
positive.
The source current goes from positive to
minus.
The topic is explained with practical way. The topic is explained only theoretical.
Contents Comparison
1.2.3 The lesson Content description of Kirchhoff’s Voltage Law
Kirchhoff's Voltage Law (KVL) states that the algebraic sum of the voltages across any set
of branches in a closed loop is zero.
∑Voltages across branches = 0
Below is a single loop circuit. The KVL computation is expressed graphically in that
voltages around a loop are summed up by traversing (figuratively walking around) the loop.
Before we start applying KVL we have to draw
current directions and voltages polarity for each
element. The direction of the current goes from
positive to negative side and the polarity of the
resistors is shown in the figure. The KVL
equation is obtained by traversing a circuit loop in
either direction and writing down unchanged

EET - EM-7 VFP-2
the voltage of each element whose “+” terminal is entered first and writing down the
negative of every element’s voltage where the minus sign is first met. The loop must start
and end at the same point. It does not matter where you start on the loop.
Now we can apply KVL if we start from point 1 we have to finish at the same point :
9 V - 1.5 V - 5 V - 2.5 V = 0
Note that a current direction must have been assumed. The assumed current creates a
voltage across each resistor and fixes the position of the “+” and “-” signs so that the
passive sign convention is obeyed. The assumed current direction and polarity of the
voltage across each resistor must be in agreement with the passive sign convention for
KVL analysis to work.

EET - EM-7 VFP-2
1.3 Didactic Analysis
Kirchhoff's voltage law very important lesson for Electrical Department trainees because
they will use it in the next lesson to analysis DC circuits and also in the next trimesters..In
the lesson will be two different way of teaching theory and practical to help the trainees to
understand the lesson very well and to apply the lesson steps in small experiment.
1.3.1 The environment
In this class there are 17 trainees and the rate ages of this class is 18 - 22 years old. All
trainees in this class are belonged to electrical power specialization. They got their
certificates from high schools so they are in the same level. As we observed during our
visits to this class me and my colleagues the trainees help each other ( good cooperation)
and good interacting with a trainer.
The lesson will be at Riyadh College of Technology in the second floor of Electrical
Department number 19 in class F28. The classroom is not well equipped so it need
ordering and organization. The classroom holds some materials such as tables, chairs,
projector and two whiteboards one for projector showing and the other for writing.
In RCT the study language is Arabic the system there is trimester. The will start at 8.00am
this time is very good for students because it is the first lesion and the will be fresh.

EET - EM-7 VFP-2
1.3.2 Methods and Tools
This topic (Kirchhoff's voltage law) is new for trainees and related to the lessons before so
during the lesson will used different methods are
 Lecture
 Classroom Conversation
 Group Work
 Discovery (Experiment)
 Individual Work
To perform this lesson in good condition should bring
 PowerPoint presentation
 Whiteboard and board markers to explain examples and draw the circuits.
 Worksheets for group work and individual tasks.
 Electrical board, wires and resistors to do the experiment.
 Electrical Measuring Device (voltmeters)
Also the trainees should bring their materials are
 Handbook
 Calculator
 Notebook
To hold the trainees attention the beginning of the lesson shall be with deductive approach
by making small review asking some questions about last two lessons. After that Lecture to
explain Kirchhoff's voltage laws definition and how to draw the directions of current and
voltages and we work with different series circuits.
Classroom Conversation to solve examples about Kirchhoff's voltage law and see different
answers and correct them by students.

EET - EM-7 VFP-2
Group work to let the trainees do some work and discussion between each other.
Experiment as is known the content at RCT theory this will be new method for trainees so
the practical step will make the trainees interesting to understand the lesson.
Individual work will gives the trainer chance to assess the trainees and his work at the end
of the lesson.

EET - EM-7 VFP-2
2. Lesson Plan
2.1 Learning Objectives
General Learning Objectives:
The Trainees …
1) connect the resistors in series connection (Cognitive ).
2) Measure the current and voltage in electrical circuits (psychomotor/ Cognitive).
Specific Learning Objectives:
The Trainees …
3) define Kickoff’s Kirchhoff's voltage law(Cognitive/Reorganization).
4) Apply Kickoff’s Kirchhoff's voltage laws on series circuits with different type circuits
(Cognitive/Reorganization).
5) solve simple DC circuits calculating the total current and the voltages across each element
(Cognitive/Transfer).

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2.2 Overview of the Intended Process
Opening / Entrance / Motivation
Methodology
Media
Time
MinutesExpected Trainer-action Expected Trainee-action
Asking the trainees about
Ohm's law and electrical
power law and write it on the
whiteboard .
interact with the trainer and
write the triangles of electrical
power and Ohm's law.
deductive
Approach
Classroom
Conversation
Whiteboard 3
Body (Information / Elaboration)
Methodology
Media
Time
Definition and explanation
of Kirchhoff's voltage law
by drawing series circuit
and demonstration how
Kirchhoff's voltage law
works.
Lecture
Projector
slide
1 , 2
5
Presents the series circuit
with three resistors and one
battery after that asks the
trainees to apply Kirchhoff's
voltage law.
Tracking the circuit and apply
Kirchhoff's voltage law steps.
Classroom
Conversation
Projector
slide
3
Whiteboard
4
Gives an example with
three resistors and three
unknown voltages to solve
it with the trainees.
Determining the unknown
voltages by using Kirchhoff's
voltage law.
Classroom
Conversation
Projector
slide
4
Whiteboard
6
Divides the class into three
groups and distribute the
work sheet of group work.
sharing in groups to solve the
tasks. Finding the voltage,
current and electrical power by
using different laws that they
have learned before. .
Group Work
Classroom
Conversation
Projector
slide
5
Whiteboard
10

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Asking the trainees to
solve and explain the tasks
on whiteboard.
One trainee from each group
solves and explains one
passage.
Classroom
Conversation
Worksheet
( 1 )
Gives the trainees change
to check how Kirchhoff's
voltage law works in
practical ways
connecting the resistors in
series and measure the
voltages and current according
to Kirchhoff's voltage law .
Discovery
Experiment
Projector
slide
6
Electrical
boards
Worksheet
( 2 )
12
Close (Reflection, Exercises, Homework, Feedback)
Methodology
Media
Time
Distributes the work sheet of
quiz and asks the trainees to
solve it individually.
The trainees determine the
voltages by Kirchhoff's voltage
law and electrical power.
Individual
work
Projector
slide
12
Worksheet
( 3 )
10

EET - EM-7 VFP-2
3. Bibliography
Kirchhoff’s Laws. (2000, 1 3). Retrieved 10 14, 2014, from Electrical Engineering Portal: http://electrical-
engineering-portal.com/resources/knowledge/theorems-and-laws/kirchhoffs-laws
Kuphaldt, T. R. (2002, 6 5). Kirchhoff's Voltage Law (KVL). Retrieved 10 16, 2014, from All about circuits:
http://www.allaboutcircuits.com/vol_1/chpt_6/2.html

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