UNIVERSITY OF WEST ATTICA
SCHOOL OF ENGINEERING
DEPARTMENT OF COMPUTER ENGINEERING AND INFORMATICS

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Circuit Theory

Kirchhoff's Laws - Ohm Law - Potentiometer - Rheostat

Vasileios Evangelos Athanasiou
Student ID: 19390005

GitHub · LinkedIn

Nikolaos Katsos
Student ID: 21390084

Supervisor: Christos Kampouris, Laboratory Teaching Staff

UNIWA Profile

Co-supervisor: Georgios Antoniou, Laboratory Teaching Staff

UNIWA Profile

Athens, April 2022

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Project Overview

This repository contains the documentation for a laboratory project conducted at the University of West Attica, within the Department of Computer and Informatics Technology and Computer Engineering.
The project focuses on the theoretical, simulated, and experimental verification of fundamental electrical laws.

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Table of Contents

Section	Folder	Description
1	assign/	Assignment material for the Circuit Theory course
1.1	assign/circuit theory rev2021_EXERCISE_1st.pdf	Assignment description in English
1.2	assign/θεωρία κυκλωμάτων rev2021_ΑΣΚΗΣΗ_1η.pdf	Assignment description in Greek
2	docs/	Documentation on Kirchhoff’s Laws, Ohm’s Law, potentiometer, and rheostat
2.1	docs/Kirchhoff-Ohm-Potentiometer-Rheostat.pdf	English documentation
2.2	docs/Κίρκοφ-Ωμ-Ποτενσιόμετρο-Ροοστάτης.pdf	Greek documentation
3	multisim/	Circuit simulation files and visual outputs
3.1	multisim/1stLawKirchhoff/	Multisim files and images for Kirchhoff’s First Law
3.2	multisim/2ndLawKirchhoff/	Multisim files and images for Kirchhoff’s Second Law
3.3	multisim/LawOfOhm/	Simulations for Ohm’s Law
3.3.1	multisim/LawOfOhm/RChange/	Output images for resistance variation
3.3.2	multisim/LawOfOhm/VoltChange/	Output images for voltage variation
3.3.3	multisim/LawOfOhm/*.ms14	Multisim project files for Ohm’s Law variants
3.4	multisim/Potentiometer/	Potentiometer simulation files and output images
3.5	multisim/Rheostat/	Rheostat simulation files and output images
3.6	multisim/VoltDividerVariant.ms14	Voltage divider variant simulation
4	README.md	Repository overview and usage instructions

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Project Overview

The primary objective of this project is to verify Kirchhoff's Laws and Ohm’s Law through three distinct approaches:

• Theoretical analysis
• Software simulation using Multisim
• Physical laboratory experimentation

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Core Topics Covered

• Kirchhoff’s First Law (Current Law – KCL)
  Verification that the sum of currents entering a node is equal to the sum of currents leaving it.

• Kirchhoff’s Second Law (Voltage Law – KVL)
  Verification that the algebraic sum of voltages around any closed loop is zero.

• Ohm’s Law
  Analysis of the relationship between voltage, current, and resistance.

• Circuit Applications
  Investigation of resistance connections, including the use of resistors as potentiometers and dimmers.

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Experimental Setup

Equipment Used

The following laboratory equipment was utilized during the experimental phase:

• Breadboard and Connection Cables
  Used for assembling the electrical circuits.

• Fixed Resistors
  Values of 4.7 kΩ and 1 kΩ.

• Digital Bench Multimeter
  Configured as a voltmeter to set and verify the DC source voltage.

• Analog Multimeter
  Configured as an ammeter for current measurements.

• Potentiometer
  Used for experiments involving variable resistance.

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Key Results

Kirchhoff’s First Law Verification (KCL)

In the simulated circuit (Figure 2), a 10 V DC source was applied:

• Total Current (XMM1): 1.027 mA
• Branch Currents (XMM2, XMM3, XMM4): 342.466 μA each

Verification:
The sum of the three branch currents equals the total current entering the node:

342.466 μA × 3 ≈ 1.027 mA

This confirms Kirchhoff’s First Law.

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Kirchhoff’s Second Law Verification (KVL)

Using a series circuit (Figure 5) with a 10 V DC source:

• The sum of voltage drops across resistors R₁, R₂, and R₃ was equal to the applied source voltage.
• The circuit operated correctly as a voltage divider.

Conclusion:
The experimental and simulated measurements verified Kirchhoff’s Second Law, demonstrating that the total potential difference around a closed loop is zero.

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Installation & Setup Guide

This repository contains laboratory simulations and analysis for Circuit Theory, focusing on RLC series and parallel circuits and their resonance behavior.

All simulations are implemented in NI Multisim.

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Prerequisites

Required Software

• NI Multisim 14 (or later)
  Ensure your system meets the requirements for running .ms14 files.
  Download from NI Multisim.

Optional Software

• PDF Viewer for documentation: Kirchhoff-Ohm-Potentiometer-Rheostat.pdf / Κίρκοφ-Ωμ-Ποτενσιόμετρο-Ροοστάτης.pdf

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Installation Steps

1. Clone the Repository

git clone https://github.com/Circuit-Theory/Kirchhoff-Ohm.git

2. Navigate to Project Directory

cd Kirchhoff-Ohm

Ensure the following folder structure exists:

assign/
docs/
multisim/

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3. Open a Simulation in Multisim

• Launch NI Multisim.
• Select File → Open.
• Navigate to the multisim/ folder.
• Open the desired .ms14 file (series or parallel circuit).
• Wait for the circuit topology to load.

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Open the Documentation

1. Navigate to the docs/ directory
2. Open the report corresponding to your preferred language:
   • English: Kirchhoff-Ohm-Potentiometer-Rheostat.pdf
   • Greek: Κίρκοφ-Ωμ-Ποτενσιόμετρο-Ροοστάτης.pdf