Find the thvenin equivalent this circuit over what portions
182  C H A P T E R 


e x e r c i s e 3.21
a) Write in standard form the minimum number of node equations needed to analyze the circuit in Figure 3.122.

v  R1  R2  i4  R4  

R3 
e x e r c i s e 3.22

a)  Find the Thévenin equivalent of the circuit in Figure 3.123.  

R3  I  R7  
R1  +  

b)  R2  R5  R8 


R1  R2  1  
I  R4  
R3  1 
b)  I  R4 

1  183  

R1  R2  R3  v  +  

1 


A  
I  R4  
v 

R3 
A′
e x e r c i s e 3.25  a  2 V 




b  
5 V  +  
8kΩ  


8kΩ  0.4kΩ  2.5mA  
e x e r c i s e 3.26  For the circuit in Figure 3.129, write the node equations. Do 
not solve, but write in matrix form: source terms on the left, unknown variables on the right.