Dept of Electrical & Electronics
Ganesh Kudva
Dept. of Electrical & Electronics Engg.
E-mail: ganesh.kudva@manipal.edu
Dept of Electrical & Electronics
Required: Scientific Calculator
Casio- fx-991ES
Dept of Electrical & Electronics
Casio- fx-991MS
We will learn here…
 Classify electrical circuit elements
Active & Passive
Linear & Non linear
Unilateral & Bilateral
Lumped & Distributed
 Ideal & Practical Active Elements
 Source Transformation
Dept of Electrical & Electronics
Electric Circuit
Definition:
An interconnection of simple electrical devices with at
least one closed path in which current may flow
Dept of Electrical & Electronics
Classification of Circuit Elements
 Active & Passive Elements
 Active Elements (Source): Voltage & Current Sources
 Passive Elements (Sink): Resistor, Inductor & Capacitor
 Linear & Non-linear Elements
 Linear (Satisfies Superposition): Resistor, Inductor, Capacitor
 Nonlinear: LDR (Light Dependent Resistor), Thermistor
 Unilateral & Bilateral Elements
 Unilateral (Current Flow in one direction): Diode, Transistor
 Bilateral: Resistor, Inductor, Capacitor*
 Lumped & Distributed
Discuss only lumped linear bilateral circuit elements.
Dept of Electrical & Electronics
Passive Elements
 Energy Consuming Elements:
 Resistor (R): RI2
 Energy Storing Elements
 Inductor (L): Stores Energy in its Magnetic Field
[0.5LI2]
 Capacitor (C): Stores Energy in its Electrical Field
[0.5CV2]
Dept of Electrical & Electronics
Types of Active Elements
Ideal Voltage Source:
 Maintains constant voltage irrespective of
connected load.
 Internal resistance, Rs = 0
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Ideal Voltage Source (DC)
Vs
+Vs
Types of Active Elements contd…
Ideal Current Source (DC)
Ideal Current Source:
 Maintains constant current irrespective of
the load connected.
 Internal resistance, Rs = ∞
Is
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Practical Sources
Practical Voltage Source
Vs
+-
Rs
V-I Characteristics of battery
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Practical Sources contd…
Practical Current Source
Is
Rs
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Practical Source Transformation
 Conversion of Practical Voltage source to Current source & vice versa
 The terminal characteristics of both the sources are same
+a
R +
a
Is
+
Vs -
R
-b
𝑉𝑠 = 𝑅 × 𝐼𝑠
Dept of Electrical & Electronics
-b
𝑉𝑠
𝐼𝑠 =
𝑅
Example 1
Convert a voltage source of 100 V having an internal resistance of 5 Ω to its
equivalent current source. Draw the circuit representation of both forms of
sources.
+a
+a
RS = 5 Ω
VS = 100 V
+
-
IP = 20 A
-b
Dept of Electrical & Electronics
RP = 5 Ω
-b
Example 2
Find the power dissipated in 2 Ω resistor
6
6
15 V
6
9V
6V
2
Ans: P = 12.5 W
Dept of Electrical & Electronics
Example 3
Find the power dissipated in 15 Ω resistor using source transformation
5 
10 V
15 
1 A
5 V
0 .5 A
20 
Ans: P15Ω = 0.9375 W
Dept of Electrical & Electronics
Summary
We started with
How a typical electric circuit looks like
Then looked into
Different types of circuit elements & their classifications
Ideal & practical sources
Finally concluded with
How to transform practical voltage & current sources
Dept of Electrical & Electronics