introduction of electrical circuit

1. 1

2. ‫الدراســــــــــــــــــــــــي‬ ‫المقرر‬ ‫محتويات‬
2
‫لنموذج‬ ً‫ا‬‫وفق‬
‫الدراسي‬ ‫للمقرر‬ ‫األكاديمية‬ ‫المتطلبات‬
‫عن‬ ‫الصادر‬
‫المــــــــــركز‬
‫واعتمــــــــاد‬ ‫جـــــــــودة‬ ‫لضمـــــــان‬ ‫الوطــــــــــني‬
‫التـــــــــــدريبية‬ ‫و‬ ‫التعليميـــــــــة‬ ‫المــــــــؤسسات‬
‫الى‬ ‫الدراسي‬ ‫المقرر‬ ‫مفردات‬ ‫قسمت‬
‫عشر‬ ‫اثنا‬
‫محاضرة‬
.
Lecture 1: Introduction to Electrical Circuits.
Lecture 2: Introduction to Electrical Circuits Contd.
Lecture 3: DC Electric Machines (Motor).
Lecture 4: DC Electric Machines (Generator).
Lecture 5: AC Machines.

3. ‫الدراســــــــــــــــــــــــي‬ ‫المقرر‬ ‫محتويات‬
3
Lecture 6: AC Machines Contd.
Lecture 7: Electric transformers.
Lecture 8: Electric transformers Contd.
Lecture 9: Rectifiers & Linear Integrated Circuits.
Lecture 10: Rectifiers & Linear Integrated Circuits Contd.
Lecture 11: Transistors.
Lecture 12: Transistors Contd.

4. ‫الدراســـــــــــــــــــــــــــــــــــــي‬ ‫المقرر‬ ‫أهداف‬
4
‫لنموذج‬ ً‫ا‬‫وفق‬
‫الدراسي‬ ‫للمقرر‬ ‫األكاديمية‬ ‫المتطلبات‬
‫عن‬ ‫الصادر‬
‫المــــــــــركز‬
‫واعتمــــــــاد‬ ‫جـــــــــودة‬ ‫لضمـــــــان‬ ‫الوطــــــــــني‬
‫التـــــــــــدريبية‬ ‫و‬ ‫التعليميـــــــــة‬ ‫المــــــــؤسسات‬
‫وهي‬ ‫أساسية‬ ‫أهداف‬ ‫أربعة‬ ‫الدراسي‬ ‫للمقرر‬
:
1
.
‫التعرف‬
‫وب‬ ‫واإللكترونية‬ ‫الكهربائية‬ ‫للدوائر‬ ‫األساسية‬ ‫المفاهيم‬ ‫على‬
‫الطرق‬ ‫عض‬
‫تحليلها‬ ‫في‬ ‫المستخدمة‬
.
2
.
‫والمستمر‬ ‫المتردد‬ ‫الكهربائي‬ ‫التيار‬ ‫محركات‬ ‫على‬ ‫التعرف‬
.
3
.
‫والمستمر‬ ‫المتردد‬ ‫الكهربائي‬ ‫التيار‬ ‫محوالت‬ ‫على‬ ‫التعرف‬
.
4
.
‫الترانزستور‬ ‫وكذلك‬ ،‫المتكاملة‬ ‫الخطية‬ ‫والدوائر‬ ‫المقومات‬ ‫على‬ ‫التعرف‬
‫ات‬
.

5. 5
‫المراجــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــع‬
Fundamentals of Electric Circuits
By Alexander & Matthew, MC Graw Hill

6. Lecture 1
Introduction to Electrical Circuits
6

7. Learning Objectives
7
Having worked through this the students will be
able to understand:

8. Units and Dimensions
The System International (SI) Unit
8
Unit abbreviation
Unit
Quantity
Kg
Kilogram
Mass
m
meter
Length
s
second
Time
A
Ampere
Electrical Current
K
Kelvin
Thermodynamic Temperature
cd
candela
Luminous Intensity
mol
mole
Amount of Substance
rad
radian
Plane Angle
sr
steradian
Solid Angle

9. Units and Dimensions Contd.
The System International (SI) Unit
9
Value
Abbreviation
Submultiple
Value
Abbreviation
Multiple
10-3
m
milli
1018
E
exa
10-6
µ
micro
1015
P
peta
10-9
n
nano
1012
T
tera
10-12
p
pico
109
G
giga
10-15
f
femto
106
M
mega
10-18
a
atto
103
K
kilo

10. Circuit Elements
➢A voltage or current source of energy (Active elements);
➢Resistors, Inductors and Capacitors (Passive elements).
Energy Sources
• Two basic variables in electric circuits: electric current & electric
potential difference (Voltage).
• A source of energy is required to cause a current to flow and
thereby to produce electric voltages in various parts of the
circuit.
• Energy is work and is measured in joules (J).
 When a force F (newton) moves a body through a distance d
(metres) the work done is (F x d ) joules.
10

11. Circuit Elements Contd.
11
Voltage Source
 An ideal voltage source is independent of the current through it.
 Its electromotive force (emf) or voltage is a function of time only.
 The unit is called the volt (V).

12. Circuit Elements Contd.
• If a thick copper wire were connected across its ends the
current through it would be infinite.
Therefore,
 The electric potential difference between two points is the work
required to move a unit positive charge (i.e. 1 C) between them.
12

13. 13
Circuit Elements Contd.

14. Circuit Elements Contd.
14
Current Source
 An ideal current source is independent of the voltage across it.
 When 1 C of charge passes a given plane of reference in one
second, it represents a current of 1 A
I = dQ /dt (2.1)
 When a current of (I ) amperes flows for (T ) seconds, the
charge moved is given by
𝑄 = ‫׬‬
0
𝑇
𝐼 𝑑𝑡 (2.2)

15. Circuit Elements Contd.
15

16. Circuit Elements Contd.
 Resistance
 Materials within which charges can move easily are called
conductors. e.g. Copper, Aluminum, etc.
 The resistance of a conductor is directly proportional to its length
(L) and inversely proportional to its cross-sectional area (A).
➢R α L ;
➢R α 1/ A ;
➢R α ρ ;
➢R α L / A ;
➢R = ρ L / A (Ω)
where ρ is the constant of proportionality and is called the
resistivity of the material of the conductor. 16

17. Circuit Elements Contd.
Ohm’s Law
• Ohm’s law states that the voltage v across a resistor is directly
proportional to the current I flowing through the resistor.
• V α I
• Ohm defined the constant of proportionality for a resistor
to be the resistance R.
• V = R I
17

18. Circuit Elements Contd.
18

19. Circuit Elements Contd.
19

20. Circuit Analysis
Definition of Terms
 Node: a point at which two or more elements have a common
connection is called a node. There are six nodes in the circuit,
numbered 1- 6.
 Open circuit: if the resistor R1 was removed from the circuit
then, there is said to be an open circuit between nodes 1 and 2.
 Branch: a single element or group of elements with two
terminals which form the only connections to other single
elements or groups of elements.
20

21. Circuit Analysis Contd.
 Branch current: the current flowing in a branch is called a
branch current. Currents I1, I2 and I3 in the diagrams are
branch currents.
 Mesh: a path through two or more branches which forms a
closed path.
 Mesh current: the currents Ia and Ib are called mesh currents.
 Short circuit: the connection between nodes 4, 5 and 6 is
made with a piece of wire having virtually no resistance and is
called a short circuit.
21

22. Circuit Analysis Contd.
Kirchhoff's Current Law (KCL)
 The sum of the currents entering a node is equal to the sum of
the currents leaving that node.
I 1 + I 2 + I 3 = I 4+ I 5
 The algebraic sum of the currents meeting at a node is equal to
zero.
I 1 + I 2 + I 3 −I 4 − I 5 = 0
22

23. Circuit Analysis Contd.
Kirchhoff's Voltage Law (KVL)
 The sum of the voltage sources around any closed path is
equal to the sum of the potential drops around that path.
 The algebraic sum of all the potential differences around any
closed path is equal to zero.
− I 3 R3 + V − I 1 R1 = 0
V = I 1 R1 + I 3 R3
I 2 R2 + 𝐼1 R1 −V= 0
V = I 1 R1 + I 2 R2
23

24. Circuit Analysis Contd.
24
Figure 3.6

25. Circuit Analysis Contd.
25
Figure 3.6

26. Circuit Analysis Contd.
26
Figure 3.7

27. 27

28. 28

29. 29