EKT101 Electric Circuit Theory
Semester 1, 2012/2013
Assignment 1
Superposition, Source Transformation, Thevenins and Norton Theorem
1.
Use superposition to find the current i0 in the circuit in Figure below.
i0
6Ω
Figure 3
2A
8Ω
2Ω
+
3i0
24 V
_
2.
Use superposition to find the voltage v0 in the circuit in Figure below.
6A
5Ω
Figure 3
5Ω
+
12 V
3.
3A
_
+
v0
_
5Ω
Use source transformation to find the voltage v0 in the circuit in Figure below.
6v0
-
Figure 4
6Ω
+
3Ω
6Ω
+
v0
-
+
_
20V
1
EKT101 Electric Circuit Theory
4.
Semester 1, 2012/2013
Obtain the Thevenin equivalent of the circuit in given Figure with respect to thve terminals a-b.
5Ω
a
+ Vx
Figure 4
+
20 Ω
+
45 V
2Vx
_
Voc
b
5.
Obtain the Thevenin equivalent of the circuit in figure below with respect to the terminals a-b.
5Ω
a
Figure 5
+
voc
_
5ix
+
iin
-
4Ω
ix
10 A
b
6.
In the circuit shown below, find the value of R that will absorb maximum power from the circuit.
Also find the value of this maximum power.
7.
Use superposition to find Vx in the following circuit.
2
EKT101 Electric Circuit Theory
Semester 1, 2012/2013
8.
In the circuit shown, find the Thevenin equivalent circuit with respect to the terminals a-b.
9.
Find the maximum power transferred to the resistor R in the given circuit.
10.
Find v0 in the circuit in the following Figure using
(a) Superposition.
(b) Source transformation.
11.
Find RL for maximum power transfer and the maximum power that can be transferred to the load in
Figure below.
3
EKT101 Electric Circuit Theory
12.
Semester 1, 2012/2013
The variable resistor in the circuit in Figure below is adjusted for maximum power transfer to R0.
(a)
(b)
Find the value of R0.
Find the maximum power that can be delivered to R0.
13.
Find the Thevenin equivalent looking into terminals a-b of the circuit in Figure below and solve for ix.
14.
Use (a) superposition and (b) source transform to find v0 in the circuit in Figure below.
4
EKT101 Electric Circuit Theory
Semester 1, 2012/2013
15.
Determine Vth, Rth, IN, and RN at terminals 1-2 of the circuit in the following Figure.
16.
Find the maximum power transferred to the resistor R in the circuit of the given Figure.
17.
For the circuit in Figure below, determine the value of R such that the maximum power delivered
to the load, RL , is 3 mW.
5
EKT101 Electric Circuit Theory
Semester 1, 2012/2013
Storage Energy Elements
Q1.
Determine the equivalent capacitance (Ceq) for each of the following circuits;
(a)
(c)
(d)
6
EKT101 Electric Circuit Theory
Semester 1, 2012/2013
(e)
Q2.
Series-connected 20-pF and 60-pF capacitors are placed in parallel with series-connected 30-pF and
70-pF capacitors. Determine the equivalent capacitance.
Q3.
Find C in the circuit below if all capacitors are 4 μF.
Q4.
Show with the aid of diagram, the voltage-division rule for two capacitors in series is
C2
C1
v1 
vs ,
v2 
vs
C1  C 2
C1  C 2
eq
assuming that the initial conditions are zero.
Q5.
Two capacitors, 20 μF and 30 μF are connected to a 100 V source. Find the energy stored in each
capacitor if they are connected in:
(a)
Parallel
(b)
Series
7
EKT101 Electric Circuit Theory
Q6.
Semester 1, 2012/2013
For the each of the following circuit below, determine:
(a)
(b)
The voltage across each capacitor,
The energy stored in each capacitor.
(a)
Q7.
(b)
Three capacitors, C = 5 μF, C = 10 μF, and C = 20 μF, are connected in parallel across a 150 V
1
2
3
source. Determine:
(a)
The total capacitance,
(b)
The charge on each capacitor,
(c)
The total energy stored in the parallel combination.
-2t
Q8.
In the circuit below, let i = 30e mA and v (0) = 50 V, v (0) = 20 V. Determine:
s
1
2
(a)
v (t) and v (t),
(b)
The energy in each capacitor at t = 0.5 s.
1
2
Q9.
Find the voltage across the capacitors in the circuit under dc conditions.
Q10.
The current through a 10-mH inductor is 6e
-t/2
A. Find the voltage and the power at t = 3 s.
8
EKT101 Electric Circuit Theory
Semester 1, 2012/2013
Q11.
The current through a 12 mH inductor is i(t) = 30t e-2t A, t ≥ 0. Determine:
(a)
The voltage across the inductor
(b)
The power being delivered to the inductor at t = 1 s
(c)
The energy stored in the inductor at t = 1 s.
Q12.
Find the voltage v(t), if the current through a 40 mH inductor is
0
i(t )   2t
 te
t0
t 0
Q13. Determine the inductance equivalent (Lab) for each of the following circuits;
(a)
(b)
(c)
9
EKT101 Electric Circuit Theory
Semester 1, 2012/2013
(d)
Q14.
Determine the L that can be used to represent the inductive network of the circuit at the terminal a-b.
Q15.
A voltage of 6e-20t V appears across a parallel combination of a 100 mF capacitor and a 12 Ω resistor.
Calculate the power absorbed by the parallel combination.
Q16.
Given in the circuit, i (0) = 2 A. Determine i (t) and v (t) for t > 0.
Q17.
Consider the circuit in Fig. 6.84. Given that v(t) = 12e mV for t > 0 and i (0) = –10 mA, determine:
eq
o
o
o
-3t
1
(a) i (0),
2
(b) i (t) and i (t).
1
2
10