The document describes an experiment to verify Kirchhoff's Voltage Law (KVL) using a circuit with resistors and a power supply. The experiment involves measuring voltages and currents at different resistor values and comparing the results to theoretical calculations based on KVL. Small differences between measured and calculated values are observed, which are attributed to measurement errors. The results confirm that KVL accurately describes the voltage relationships in the circuit.

1. ELECTRICAL CIRCUIT KIRCHHOFF’S VOLTAGELAW
KOYA UNIVERSITY
FACULTY OF ENGINEERING
PETROLEUM ENGINEERING
DEPARTMENT
SECOND STAGE- GROUP:- B
ELECTRICAL CIRCUITS AND
MACHINES
EXPERIMENT NO. :- Three
Prepared By:
SARWAR SALAM

2. ELECTRICAL CIRCUIT KIRCHHOFF’S VOLTAGELAW
2
Dec. 22nd
2014
Aim of experiment:-
The objectives of this laboratory experiment are to
verify Kirchhoff's Voltage law (KVL), and also to
became familiar with the applications of Kirchhoff's
Voltage law.
As well to be able to write KVL for every loop in the
circuit.
also to Be able to solve the KVL equations, especially
for simple circuits.

3. ELECTRICAL CIRCUIT KIRCHHOFF’S VOLTAGELAW
3
Introduction:-
The analysis of electrical circuits involves the
determination of the voltages across and the currents
through the constituent circuit elements. This analysis
is based on the law which has been set by the German
scientist Gustav Robert Kirchhoff.
That says’’ that the algebraic sum of the voltage
drops across circuit elements around any closed loop
in an electrical circuit at any instant of time is zero’’.
A simple circuit is one that can be reduced to an
equivalent circuit containing a single resistance and a
single voltage source. Many circuits are not simple
and require the use of Kirchhoff’s Laws to determine
voltage, current, or resistance values. Kirchhoff’s
Laws for current and voltage are given by equations 1
and 2.

4. ELECTRICAL CIRCUIT KIRCHHOFF’S VOLTAGELAW
4
Theory:-
Kirchhoff’s laws relate to the conservation of energy,
which states that energy cannot be created nor
destroyed, only changed into different forms. This can
be expanded to laws of conservation of voltage and
current. In any circuit, the voltage across each series
component (carrying the same current) can be added
to find the total voltage. Similarly, the total current
entering a junction in a circuit must equal the sum of
current leaving the junction.
The law to be described in this section is one of the most
important in this field. It has application not only to
DC (direct current) circuits but also to any type of
signal—whether it is AC (alternating current), digital,
and so on. This law is far-reaching and can be very
helpful in working out solutions to networks that
sometimes leave us lost for a direction of investigation.

5. ELECTRICAL CIRCUIT KIRCHHOFF’S VOLTAGELAW
5
The law, called Kirchhoff’s voltage law (KVL), was
developed by Gustav Kirchhoff in the mid-1800s(
exactly in 1874). It is a cornerstone of the entire field
and, in fact, will never be outdated or replaced.
The application of the law requires that we define a
closed path of investigation, permitting us to start at one
point in the network, travel through the network, and
find our way back to the original starting point. The path
does not have to be circular, square, or any other defined
shape; it must simply provide a way to leave a point and
get back to it without leaving the network.
Anther fact that can be obtained from KVL, says’’ the
sum of the voltage rises around a closed path will
always equal the sum of the voltage drops’’
And there is a point to mention, There is no
requirement that the followed path have charge flow
or current. In the case of open circuit which known
that the current is zero everywhere, but Kirchhoff’s
voltage law can still be applied to determine the
voltage between the points of interest. Also, there will
be situations where the actual polarity will not be
provided. In such cases, simply assume a polarity. If

6. ELECTRICAL CIRCUIT KIRCHHOFF’S VOLTAGELAW
6
the answer is negative, the magnitude of the result is
correct, but the polarity should be reversed.
Apparatus
1. DC circuit training system (Bread-board)
2. Set of wires.
3. DC Power supply (E=10V)
4. Digital A.V.O. meter (multi-meter)
5. fixed resistor (1.5kΩ)
Experimentalprocedure:-
1- Adjust VR1 to 1kΩ and apply +10Vto +V.
2- Connect the circuit as shown in figure below.
3- Measure and record the ammeter reading.
4- Using the voltmeter, measure and record
voltage across R1 and VR1.

7. ELECTRICAL CIRCUIT KIRCHHOFF’S VOLTAGELAW
7
5- Adjust VR1 to 500Ω and repeat the last two
steps.
6- Adjust VR1 to 200Ω and repeat step 3 and 4.
Conclusion:-
Each circuit setup in the experiment clearly showed
Kirchhoff’s Laws in a physical example. By taking
measurements of values and computing the same
values, it was easy to see how Kirchhoff’s Laws relate
to the circuits. In Each example also can use
extensively the Node Voltage and Mesh Current
Analysis Methods to help see the laws in action and
how these analysing methods are seen and utilized in
a physical circuit. Although for some examples the
measured values and computed values were slightly
different, because of measurement and mathematical

8. ELECTRICAL CIRCUIT KIRCHHOFF’S VOLTAGELAW
8
errors, it was easy to see the relationship between the
circuit model and the law being tested.
The experiments gave good experience is setting
up different kinds of circuits and how to properly take
voltage and amperage measurements in them. Also,
use of the circuit analysis methods was reinforced in
the lab. Finally, the relationship between voltage,
amperage, and resistance was explored even further
by analysing all three in an electrical network.
Discussion:-
1- Calculatethe resistance RT and the current Is for the
circuit.
Ans. Because each of the fixed resistor of a value of
1.5kΩ and the variable resistor of 1kΩ (in first
attempt) are in series so the summation of resistor
values will be equal to 2.5kΩ, hence the current
across the series combination according to Ohm’s
law is equal to 4mA, same procedureis applied to 5th
&6th
steps.
Whereas, in step 5, the total resistor is 2Ω
(1.5kΩ+500Ω=2kΩ) with a current of 5mA across

9. ELECTRICAL CIRCUIT KIRCHHOFF’S VOLTAGELAW
9
each resistor, and in last step of the experiment
procedure, the value of RT is 1.7kΩ
(1.5kΩ+200Ω=1.7kΩ) base on Ohm’s law.
2- Compare the theoreticaland practical values.
Ans. The theoretical values which obtained from point one
in this section, and the practical or actual values that have
been measured and recorded in the experiment, are almost
the same , with considering some differences in both
resistor values (i.e. the fixed resistor because of the
tolerancewhich can either greater or smaller value than its
supposed to be) and also the current value(i.e. as dependent
of the resistor values). For instances the theoretical value of
the fixed resistor is supposed to be 1.5kΩ, but when testing
its actual value we have obtained that it is 1.49kΩ!This is
in the range of its own tolerance. And consequentlythe
current value will change from 4mA to 4.016mA which
simply can ignore this little difference.
-Fixed resistor >>> independent value
- Current & Total resistor>>>Dependentvalue
3- Discuss your results.

10. ELECTRICAL CIRCUIT KIRCHHOFF’S VOLTAGELAW
10
Ans. During this experiment which was application
of one of the most important and primary laws in
Electrical science which is Kirchhoff’s Voltage Law,
we have started with connectingthe required circuit,
but unfortunately we have made some errors, but
then we corrected them, and we had measured the
value of given fixed resistor to double check with its
value and to get the exact actual value, which was in
the resistors tolerance range, then, as it is possible
and adequate to get different value from the
theoretical results we got the value of RT of2.5kΩ in
the first attempt and the current across each resistor
of 4mA, which is a little bit differ than the
theoretical result
(i.e. RT =2.49kΩ and I=4mA) .
and the values of voltage through resistors which as
it was supposed to be from KVL was equal to the
value of the supplied potential source (V1=Vfixed
resistor=5.95V&V2=VR1=4V)
applying KVL for the circuit gives,
+E-V1-V2=0>>>>10-5.95-4=0.05V this difference
is could be result of human errors or reading errors
or anything else could cause verity in results, as we
saw it is very small difference sow could set it as
zero volts.

11. ELECTRICAL CIRCUIT KIRCHHOFF’S VOLTAGELAW
11
References:-
1- http://www.facstaff.bucknell.edu/mastascu/eLes
sonsHTML/Basic/Basic5Kv.html
2- http://www.allaboutcircuits.com/vol_1/chpt_6/2
.html
3- http://www.ee.sc.edu/personal/faculty/simin/EL
CT102/10%20KVL%20&%20Series%20circuit
s.pdf

12. ELECTRICAL CIRCUIT KIRCHHOFF’S VOLTAGELAW
12
4- http://physics.mercer.edu/labs/manuals/manualE
Mlab/Kirchhoff.pdf
5- http://www.ece.ualberta.ca/~mcmullin/EE240-
2011/EE-240%20Lab-
2%20Circuit%20Theorems.PDF
6- http://www.umsl.edu/~physics/files/pdfs/Electri
city%20and%20Magnetism%20Lab/Exp5.Kirch
off.pdf
7- http://www.uotechnology.edu.iq/deplaseran
doptoeleceng/laboratory/1/DC/Experiment
%20No.7.pdf

13. ELECTRICAL CIRCUIT KIRCHHOFF’S VOLTAGELAW
13