Kuwait University

College of Engineering & Petroleum

Electrical Engineering Department

207 Lab Report

Summer 2014-2015

Experiment No.: 1

Title: Ohm’s Low

اإلسم بالعربي رباعي محمد محمد محمد محمد المسلسل بالكشف 10

الرقم الجامعي 12000000005 رقم البنش 9

شعبة 207/1

التاريخ 24/5/2015

اليوم االحد والثالثاء

الوقت 1-3.40

إسم المهندس

Table of contents

Objective 1

Theory 1

Equipments 2

Procedure 2

Data Sheet 3

Simulation 4

Exercise 6

Conclusion 7

References 7

Experiment #1

Familiarization and Ohm’s Law

1

Objective :

1. To be familiar with the laboratory equipment and components.

2. Verification of Ohm’s law.

3. Series and parallel circuits.

Theory:

Part II : Ohms's Law: Ohm's Law says: The current in a circuit is directly proportional to the applied voltage. V = I * R (1)

Figure 1: Ohm’s Law

Part III : Series & Parallel Circuits:

Figure 2: Series and Parallel Connections

Experiment #1

Familiarization and Ohm’s Law

2

Equipments: 1) DC Voltage Source 2) Bread Board.

3) DMM 4) Discrete resistors

Procedure: Part I : Ohm’s Law:

Figure 3: Circuit Diagram

1) Select a discrete resistor R = 5 KΩ, measure the resistor value

2) Connect the circuit as shown in Figure 1-16 with the shown values.

3) Vary the DC voltage source and measure I. and fill table(1)

Part II: Parallel and Series Circuits:

Figure 4: Circuit Diagram

1) Connect the circuit as shown in Figure 1-11-a, R1= R2=2KΩ, R3=3.9KΩ, R4= R5=2KΩ,

2) Connect the circuit as shown in Figure 1-17-b, R1=1KΩ, R3=1KΩ, R2=3.9KΩ

Experiment #1

Familiarization and Ohm’s Law

3

Data Sheet :

Part I:

R Measured = 5.032 kΩ

Table(1)

VS

I (mA)

Theoretical (PSpice) Practical (Measured)

2 0.4 0.414

4 0.8 0.813

6 1.2000 1.206

8 1.6000 1.601

10 2.000 2.004

Part II:

RAB1 (kΩ) RAB2 (kΩ)

Theoretical

(PSpice)

Practical

(Measured)

Theoretical

(PSpice)

Practical

(Measured)

5.8 5.843 5.8 5.834

Experiment #1

Familiarization and Ohm’s Law

4

Simulation :

Part 1:

Simulation for Circuit 1-10:

PSpice DC Sweep Analysis Curve:

Slope of the curve = ∆y/∆x = ∆I/∆V = (-2.857/-2.857)x10−3= 1x10−3

V_V1

0V 1V 2V 3V 4V 5V 6V 7V 8V 9V 10V

V(R1:2)

0V

5V

10V

2121113090

Alaa Al-Ansari

Experiment #1

Familiarization and Ohm’s Law

5

Part II:

Simulation for circuit of Figure 1-11-a

R AB1 = 𝑽𝒔

𝑰 = (10)/(1.695)= 5.8 kΩ

Simulation for circuit of Figure 1-12-b

R AB2 = 𝑽𝒔

𝑰 = (10)/(1.695)=5.89 kΩ

Experiment #1

Familiarization and Ohm’s Law

6

Exercise :

Q1: Draw V versus I, find the slope of the curve and what does the slope represent?

Slope represent 1

𝑅

R = 1

𝑠𝑙𝑜𝑝𝑒=

1

0.1995 = 5.01 𝑘Ω

Q2: Compare the slope of Q1 with the theoretical value. % 100 Theoritical Measured error

Theoretical (%r = 𝒕𝒉𝒆𝒐𝒓𝒊𝒕𝒊𝒄𝒂𝒍−𝒎𝒆𝒂𝒔𝒖𝒓𝒆𝒅

𝒕𝒉𝒆𝒐𝒓𝒊𝒕𝒊𝒄𝒂𝒍𝒙𝟏𝟎𝟎)

The slope is the same

Error theoretical = (1∗10−3)−(0.1995∗ 10−3)

(1∗10−3)∗ 100 = 80.05

Q3: What are the error sources in Q2?

Because of tolerance of resistor and calibrated

Q4: Calculate RAB1 and RAB2 theoretically.

Rab1 = 5.8 kΩ

Rab2 = 5.8 kΩ

Q5: What is the relation between the circuit of Figure 1-11a and Figure 1-11b

The value of equivalent resistance are the same.

On the series resistor R = R1 +R2

On the parallel resistor R = 1

1

𝑅1+

1

𝑅2

Experiment #1

Familiarization and Ohm’s Law

7

Conclusion :

- To generate a variable DC voltage we have to use DC power supply

- The relation between voltage and the current is not inversely (as voltage increase the

current increase too )

- On the parallel resistors :

a) V is constant

b) I(equivalent) = I1 + 12

c) R(equivalent) = R = 1

1

𝑅1+

1

𝑅2

(smaller than the smallest value of resistor on the circuit)

- On the series resistors :

a) I is constant

b) V (equivalent) = V1+ V2

c) R(equivalent )= R1 +R2 (bigger than the biggest value of resistor on the circuit.

References:

1) Fundamental of Electrical circuits Lab manual.