Electrical Engineering Department

[Circuit Lab &E226]

Lab Report for Experiment No.:[3]

Experiment Title:Kirchoff’s Law

Submission Date:12/3/2025

Student Name(s) Student ID Number(s)

ibrahim alanazi 443015008

Lab Instructor eng obaidullah khan

 Table of Contents
Objective............................................................................................................................................... 2
Significance........................................................................................................................................... 2
Background / Theory.............................................................................................................................2
Method & Apparatus............................................................................................................................ 2
Procedure..............................................................................................................................................2
Observations......................................................................................................................................... 2
Calculations...........................................................................................................................................2
Results...................................................................................................................................................2
Discussion / Analysis............................................................................................................................. 2
Conclusions........................................................................................................................................... 2
References............................................................................................................................................ 2
Appendix............................................................................................................................................... 2

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Objective
[-To confirm Kirchoff’s Voltage Law (KVL) & Kirchoff’s Current Law (KCL).

-To implement the circuits on the bread board and how to use multimeters.]

Significance
[To have an understanding of the differences between KVL and KCL and how they work, and how
the currents act at nodes and the voltages in loops ]

Background / Theory
[Gustav Kirchoff the German physicist who established the basics of electrical circuits analyzing.

KCL: states that the algebraic summation of current entering a node of a conductor network equals

the same algebraic summation of the current leaving the node. ∑ 𝐼𝑖𝑛 = ∑ 𝐼𝑜𝑢𝑡

KVL: states that in any closed loop or (mesh) the voltage (potential difference) summation must

equal zero. ∑ 𝑉(𝑚𝑒𝑠ℎ) = 0

Method & Apparatus

[Apparatus:

1-DC supply

2-Resistors of (1KΩ, 470Ω, 680Ω

3-Multimeter

4-Bread Board (DC circuit training system)

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5-Jumpers and wires.]

Procedure
[1-Make sure the power supply is set to 10V by using multimeter.
2- construct or build the circuit
3- Verify that Vs- Vp = 0, Vp -Vq - Vr= 0, Vr - Vu - Vt = 0 .
VD + VE + VF = 0 ; Because they are grounded.
4- Verify that i = i1+ i2 , i2= i3 + i4 , i3 + i4 = i5 , i1 + i5 = i6, i6 = i.
5- Put the Multimeter in parallel of each resistor and
in voltmeter and record [Vs, Vp, Vq, Vr, Vu, Vt].
6- Put the Multimeter in series with the resistor and voltage
Source, and put the multimeter in Ammeter mode and measure the current [i, i1, i2, i3, i4, i5, i6]
7- Put the values in tables.]

Observations

KVL Voltage Measurements (V)

Vs Vp Vq Vr Vu Vt VD =VE = VF
Simulation Results 10 10 4.677 5.323 2.175 3.148 0
Experimental Results 10.054 10.054 4.682 5.339 2.176 3.13 0
%Error 0.54 0.54 0.107 0.3 0.005 0.572 0
KCL Current Measurements (mA)
i i1 i2 i3 i4 i5 i6
Simulation Results 19.95 10 9.95 5.323 4.629 9.952 19.95
Experimental Results 19.48 10 9.858 5.244 4.595 9.858 19.47
%Error 2.35 0 0.925 1.48 0.7345 0.9445 2.41
.]

Calculations
[

10 = 1000 (A – B)

3
0 = -1000A + 2470B – 1000C

0 = 0A – 1000B + 2150C

Solving the equations so,

A=19.95mA, B=9.95mA, C= 4.628mA. and to get the voltage across each element :

Vs = 10 V and the current flowing in it is A so i = 19.95mA

10
Vp = 1000 (0.01995-0.00995)=10V , i1= 1000
= 10𝑚𝐴

4.677
Vq = 470 x 0.00995 =4.677V , i2= 470
= 9. 95𝑚𝐴

5.32
Vr = 1000 x (0.00995 – 0.004628)=5.32V , i3= 1000
= 5. 32𝑚𝐴

2.175
Vu = 470 x (0.004628)=2.175V , i4= 470
= 4. 628𝑚𝐴

3.14
Vt = 680 x (0.004628) = 3.14V , i5= 680
= 4. 628𝑚𝐴

i = i1 + i2 = 19.95mA

i2 = i3 + i4 = i5 = 9.95mA

i5 = i3 + i4= i2 = 9.95mA

i6 = i1 + i5 = 19.95mA ]

Results

In loop A Vs- Vp = 0, Vp -Vq - Vr= 0, Vr - Vu - Vt = 0 .

VD + VE + VF = 0 ,

i = i1+ i2 , i2= i3 + i4 , i3 + i4 = i5 , i1 + i5 = i6, i6 = i

*note that if the equations weren’t equal the voltage or current were lost in the jumpers or the
bread board due to their resistivity.

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.]

Discussion / Analysis
[Mainly, the results that we got the results that we expected. KCL is the sum of the currents entering
node equals the sum of the currents leaving the node for nodes the sum of current entering the
node is the same as leaving the node, with losses due to bread board, jumpers and the accuracy of
the resistors, the error percentage is between 0 and 3%, and that’s due to the reasons mentioned
earlier.

On the other side of the experiment, we validate KVL which is the sum of the voltages in a closed
loop must equal zero. And that was verified in the experiment. So, for loop A since we only had two
elements a voltage source and a resistor with current flowing it so voltage source equals the voltage
across the resistor Vs-Vp=0; Vs=Vp = 10.054V.

Many of the circuits analyzing laws or methods are somehow based on KVL & KCL.]

Conclusions
[To sum up, the experiment verifies Kirchoff’s law (KCL & KVL) which solves a lot of circuits, it’s
efficient to use Kirchoff’s laws to build a circuits with specific element and as the experiment shows
it could have accuracy percent error.]

References
[https://en.wikipedia.org/wiki/Gustav_Kirchhoff [1]

Fundamentals of. Electric Circuits K. Alexander | Matthew n. o. Sadiku [2]

https://en.wikipedia.org/wiki/Kirchhoff%27s_circuit_laws#Kirchhoff's_current_law_(KCL) [3]

https://www.toppr.com/guides/physics/electricity/heating-effects-of-electric-current-and-its-applic
ations/[4]

https://peda.net/kenya/ass/subjects2/physics/form-32/heoaec

https://www.quora.com/Why-does-the-thermal-conductivity-of-metals-decrease-with-an-increase-i
n-temperature

http://support.fluke.com/find-sales/Download/Asset/2633834_6115_ENG_A_W.PDF

.]

Appendix
[1. What is grounding, and what is grounding voltage value

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Is a reference point that the potential differences (voltages) are measured. the value of the ground
is approximately zero.

Why do we subtract VA- VB to get Vq, what does this mean? And say how a higher potential is
responsible for current direction.

By convention the current flows in the opposite direction of the electrons flow. Current flows from
higher voltage to lower voltage. Assume there was a battery and a resistor and a grounded at
bottom so the polarity will be the same by doing KVL the current will be flowing from positive to
negative terminal.

Can you compare i and i6 what is similar between them and what is difference between them? And
how do you relate it to battery current.

i and i6 have the same value but the difference is i is the current of the battery going out from the
battery or the positive terminal but i6 is the current entering the battery the negative terminal.

4.Do you observe resistor heating and if it so do we get exact value of i and i6.

Yes, and that because resistors change electrical energy into heat. H = I2Rt.[4] This equation is the
Joule’s equation of electrical heating.

And the equation depends on the time so the longer time the more heat produced, in high
temperature the molecules will vibrate faster and that will reduce the conductivity and that is the
difference between i and i6 .

Why VD, VE and VF are zero voltage, can you explain the earthing or grounding concept depending
upon them? And say what is maximum permissible value of grounding current?

Because they are connected to DC source and that usually connected to a ground so we can have a
safe connection preventing any failures or shocks. And since they have zero resistivity the voltages
when we do KVL remains the same and do not get effected. Ideal ground resistance is zero and the
acceptable ground resistance value of 5.0 ohms or less.

6. Which of the following below holds true for Kirchoff voltage law in a single loop

a. ΣV= 0

b. ΣI= 0

c. ΣV= Vsource

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d. ΣI= Isource

7. Which of the following below holds true for Kirchhoff Current law at a node:

a. ΣI entering = ΣI leaving

b. ΣI entering = 2ΣI leaving

c. ΣI= 0

d. Answer a. and c.

8. From the figure below which one of the following is correct;

a. Is =I1+I2

b. Is =I1-I2

c. Is =0

d. Ix =I1+I2

9. From the figure below which one of the following is correct:

a. Vs =v1+v2

b. Vs =v1-v2

c. Vs = -v1+v2

d. Vs =v2

.]

For Official Use Only:

Sub-title No. 1 2 3 4 5 6 7 8 9 10 Total

CLO Focused:

SO-KPI Focused

Max. Points:

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Points Obtained: