Chapter 4
Exercise 8 : In the circuit of Fig. 4.34, determine the current labeled i with the assistance of nodal
analysis techniques.
Solution:
Considering bottom line as reference node.
Applying nodal analysis at nodes V1 and V2 we get:
5=
V 1 V 1V 2
+
eq 1
1
5
V 1V 2 V 2
=
+4eq 2
5
2
Rearrrangingthe equations we get :
6 V 1V 2=25
2V 17 V 2=40
Solving these two equations we get :
V 1=
27
19
V V 2=
V
8
4
Thus i=
V 1V 2 13
= A=1.625 A (ans)
5
8
Figure 4.34
Exercise 26
Determine the value of k that will result in vx, being equal to zero in the circuit of Fig. 4.52.
Solution:
Applying nodal analysis at nodes VxVy we get :
2Vx VxVy Vx
=
+
1
4
1
VxVy
VykVy
=1+
4
3
Now assuming Vx=0, putting first equation we get :
20 0Vy 0
=
+
1
4
1
>Vy =8 V
Putting the value of Vx=0Vy=8 V second equation we get :
08
8k
=1+
4
3
>k =
17
(ans)
8
FIGURE 4.52
Exercise: 28 For the circuit of Fig. 4.54, determine all four nodal voltages.
FIGURE 4.54
Solution:
The central node istaken as ground :
So V 1=1 V
Now for others applying nodal analysis at each of the nodes V 2,V 3V 4 we get :
1V 2
V 2V 3
+3=
1
2
V 3V 4
V 2V 3
+2 ( V 3V 4 )=
1
2
V 3V 4 V 4 V 41
=
+
1
3
4
Rearranging these equations we get :
3 V 2V 3=8
V 27 V 3+6 V 4=0
12V 319V 4=3
Solving the simultaneous equations we get :
V 1=
253
=3.085V
82
V 2=
103
=1.256V
82
V 3=
( ans )
39
=0.9512 V
41
Chapter 5
Question: 40
Determine the Norton equivalent of the circuit drawn in Fig. 5.81 as seen by terminals a and b. (There
should be no dependent sources in your answer.)
Solution:
Taking above portion as reference and bottom as voltage V,
Also inserting a voltage source of 1V
Now we have nodal equation as
Ix +0.7=
V +1
2500
also Ix=
2 IxV
500
Putting Ix solving for V we get ,
V =290.5276 V
thus current flowing across1 V sorce is
I=
V +1
1
+
2500 1.5 k
0.117266 A
1
Now norton resistance= =8.5275ohms
I
Now for Norton current we short the terminals
Thus applying nodal analysis we have:
Ix +0.7=
V
2500
also Ix=
2 IxV
500
Solving we get :
Ix=
875
=0.58372 A
1495
So Ix+.7=0.116277 A
116.277 mA
So nortoncurrent=116.3 mA
Question: 48
Study the circuit of Fig. 5.89. (a) Determine the Norton equivalent connected to resistor Rout. (b) Select a
value for Rout such that maximum power will be delivered to it.
Solution:
a)
To determine the Norton resistor, we will short the voltage source and open circuit the current source.
Now the resistor across AB will be:
Rab=
1 k2 k
1 k +2 k
2
k ohms
3
2
b m aximum power will be delivered if Rout =Rab=Rnorton= k ohms( ans)
3
Question: 60
Determine the effective resistance Rin of the network exhibited in Fig. 5.99.
Solution:
Before doing this question it is important to learn star-delta and vice-versa
conversion.
Equations for the transformation from -load to Y-load
Equations for the transformation from Y-load to -load
Transferring the first part into star from delta we get:
R=( R*R+ R*R+ R*R)(R+R+R) = R/3
Which is:
Now above portion is in parallel. So,
Now the last is in parallel, which gives:
R=8/7 R (ans)