2. ELE 101 / 102 Dept of E & E Engg, MIT Manipal 2
Electric Circuit
Electric Circuit
An interconnection of simple electrical devices with at
least one closed path in which current may flow
Circuit Elements
Active Elements
Voltage and Current sources
Passive Elements
Resistors, Inductors and Capacitors
3. ELE 101 / 102 Dept of E & E Engg, MIT Manipal 3
Circuit Elements Review topics
Basic Circuit ElementsBasic Circuit Elements
Active ElementsActive Elements Passive ElementsPassive Elements
SourcesSources
Dependent
sources
Dependent
sources
Independent
sources
Independent
sources
Voltage sourcesVoltage sources Current sourcesCurrent sources
Ideal (DC)
Voltage source
Ideal (DC)
Voltage source
Ideal (DC)
Current source
Ideal (DC)
Current source
Practical (DC)
Current source
Practical (DC)
Current source
Practical (DC)
Voltage source
Practical (DC)
Voltage source
1. Resistors
2. Inductors
3. Capacitors
1. Resistors
2. Inductors
3. Capacitors
4. ELE 101 / 102 Dept of E & E Engg, MIT Manipal 4
Passive Elements
Resistance (R):
Property of opposition to flow of current
The voltage across the resistor is proportional to the current flowing
through it
VR = IR
‘R’ = VR/I
Unit - Ohm
5. ELE 101 / 102 Dept of E & E Engg, MIT Manipal 5
Passive Elements
Inductance (L):
Property of opposition to the rate of change of current
The voltage induced in the inductor is proportional to the rate of
change of current flowing through it
eL = L (di/dt) = N (dФ/dt)
L = N (dФ/di)
Unit – Henry (H)
6. ELE 101 / 102 Dept of E & E Engg, MIT Manipal 6
Passive Elements
Capacitance (C):
Property which opposes the rate of change of voltage
The capacitive current is proportional to the rate of change of
voltage across it
ic = C (dv/dt)
Unit – Farad (F).
7. ELE 101 / 102 Dept of E & E Engg, MIT Manipal 7
Ideal Nature
Property of the element which does the intended work only
ideal voltage source maintains a prescribed voltage
regardless of the current in the device. Internal resistance
Rs = 0
ideal current source maintains a prescribed current
regardless of the voltage across the device. Internal
resistance Rs = ∞
ideal resistor constraints its voltage and current to be
proportional to each other. (v = iR; Ohm’s law)
8. ELE 101 / 102 Dept of E & E Engg, MIT Manipal 8
Ideal Sources
Independent Voltage & Current Source:
I d e a l C u r r e n t S o u r c e ( D C )
+ -
I d e a l V o l t a g e S o u r c e ( D C )
V s
V s I s
9. ELE 101 / 102 Dept of E & E Engg, MIT Manipal 9
Practical Sources
Independent Voltage & Current Sources
P r a c t i c a l C u r r e n t S o u r c e
+ -
P r a c t i c a l V o l t a g e S o u r c e
V s
I s
R s
R s
10. ELE 101 / 102 Dept of E & E Engg, MIT Manipal 10
Source Transformation
Conversion of Practical
Voltage source to Current
source & vice versa Vs
Rs
+
-
+
-
a
b
Ip Rp
+
-
a
b
Voltage & Current sources
shown in the figure are
electrically equivalent if
Vs = Ip * Rp or (Ip = Vs/Rs)
Rs = Rp
11. ELE 101 / 102 Dept of E & E Engg, MIT Manipal 11
Dependent Sources:
Voltage Controlled Voltage Source
(VCVS)
+
V = u V a b
c
d
a
b
+
- -
V
Voltage Controlled Current Source
(VCCS)
+
I = u V a b
c
d
a
b
+
- -
I
Voltage Controlled:
12. ELE 101 / 102 Dept of E & E Engg, MIT Manipal 12
Dependent Sources:
Current Controlled Voltage Source
(CCVS)
+
V = u I a
c
d
a
b
+
- -
I a
V
Current Controlled Current Source
(CCCS)
+
I = u I a
c
d
a
b
+
- -
I a
I
Current Controlled:
