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ANALYSIS METHODS

[CHAP. 4

Fig. 4-13   30 ð3Þ ¼ 10 V 9   30 6  10 ¼ 10 V ¼ V0 ¼ 9

Vab ¼ V 0 ¼ 20  or

Vab

The resistance R 0 can be obtained by shorting out the voltage sources [Fig. 4.13(c)] and finding the equivalent resistance of this network at terminals ab: R0 ¼ 3 þ

ð3Þð6Þ ¼ 5 9

When a short circuit is applied to the terminals, current Is:c: results from the two sources. runs through the short from a to b, we have, by superposition, 2 3 2 3     6 20 3 10 6 6 7 7 Is:c: ¼ I 0 ¼ 4 5 4 5 ¼ 2A ð3Þð6Þ ð3Þð3Þ 6þ3 3þ3 3þ 6þ 9 6

Assuming that it

Figure 4-14 shows the two equivalent circuits. In the present case, V 0 , R 0 , and I 0 were obtained independently. Since they are related by Ohm’s law, any two may be used to obtain the third.

Fig. 4-14

The usefulness of The´venin and Norton equivalent circuits is clear when an active network is to be examined under a number of load conditions, each represented by a resistor. This is suggested in

Mahmood_Nahvi_eBook_Schaum_s_Outlines_Theory_An  
Mahmood_Nahvi_eBook_Schaum_s_Outlines_Theory_An  
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