Introduction to Electric Circuits

[~ 10~

IA

T

B

Figure 3.17

40~

Example 3.6

9 Step 5: put these values for Eo and Ro in the Thevenin equivalent circuit of
Fig. 3.15. Then

IL = Eo//(Ro + RE)= 4.8/(8 + 40)= 0.1 A

This is therefore the current which will flow through the resistor RL

in the original circuit of Fig. 3.14.

Thevenin's theorem is very useful when we wish to determine the current
through or the voltage across an element which is variable.

Figure 3.18

The resistor r shown in the diagram of Fig. 3.18 is variable from 0 to 250 l'l.

Determine the maximum and minimum values of the current IL.

R3 = 20~

A

1

V1 = 20V O V2 = 10V

/

~

N1 = 5f~ ~R2 = lOf~

B

Solution

Ro

The Thevenin equivalent circuit is shown in Fig. 3.19 and we put terminals A

Figure 3.19

A

IL

50 DC circuit analysis