
Circuit Theorems
221
owing into R
2
, but due to I
s
. Finally
we sum the results.
Figure 6.45 is the rst equivalent
network with I
s
=
0 and the current
from the voltage source is
I
V
RRRRR
V
S
g
S
=
++ +
12
||
Therefore
I
RR
RRR
I
R
V
V
S
S
2
34
234
()
=
++
Figure 6.46 illustrates the second
equivalent network with V
s
= 0 and
now the current I
R3
owing into the
resistor R
3
is
I
R
RRRRR
I
R
g
s3
4
43
=−
++ +
||
As a consequence
I
RR
RRR
I
R
I
g
g
R
S
2
1
3
()
=
++
The requested current is then
III
RR
RRR
I
RR
RR
V
R
I
V
g
SS
S
22 2
34
234
=+=
+
++
()
+
() ()
11
3
34
23412
RRR
I
RR
RRR
V
RRR
g
R
S
g
++
=
+
++
()
++|| RRR
RR
RRR
R
RRRRR
g
34
1
21
4
43
+
()
−
+
++
()
++ +
()
||
II
S
EXERCISE 6
The network in Figure 6.47 is made with a real cur