1. 1 ELECTRICAL TECHNOLOGY EET 103/4  Explain and analyze series and parallel circuits  Explain, derive and analyze Ohm’s Law, Kirchhoff Current Law, Kirchhoff Voltage Law, Source Transformation, Thevenin theorem.

2. 2 (CHAPTER 8) METHOD OF ANALYSIS SOURCE CONVERSION

3. 3 8.2 Current Sources  The current source is often described as the dual of the voltage source.  A battery supplies a fixed voltage, and the source current can vary; but the current source supplies a fixed current to the branch in which it is located, while its terminal voltage may vary as determined by the network to which it is applied.

4. 4 8.2 Current Sources

5. 5  A current source determines the current in the branch in which it is located  The magnitude and polarity of the voltage across a current source are a function of the network to which it is applied

6. 6 8.2 Current Sources

7. 7 Example 8.1 Find V s, V 1 and I 1 :

8. 8 8.2 Current Sources Example 8.1 – solution

9. 9 8.2 Current Sources Example 8.2 Find V s, I 1 and I 2 :

10. 10 8.2 Current Sources Example 8.2 – solution

11. 11 8.3 Sources Conversion  An ideal source cannot be converted from one type to the other.  All practical sources – whether they are voltage or current – have some internal resistance.

12. 12 8.3 Sources Conversion Practical voltage sourcePractical current source

13. 13 8.3 Sources Conversion  The equivalence between a current source and a voltage source exists only at their external terminals.  A source and its equivalent will establish current in the same direction though the applied load.

14. 14 8.3 Sources Conversion

15. 15 8.3 Sources Conversion Example 8.4 (a) Determine I L. (b) Convert the voltage source to a current source. (c) Using the current source in (b), calculate the current through R L.

16. 16 8.3 Sources Conversion Example 8.4 – solution

17. 17 8.3 Sources Conversion Example 8.4 – solution (cont’d) I

18. 18 8.3 Sources Conversion Example 8.4 – solution (cont’d) Voltage source Current sourceconverted to

19. 19 8.3 Sources Conversion Example 8.4 – solution (cont’d) Voltage source and its equivalent current source with the same load

20. 20 8.3 Sources Conversion Example 8.4 – solution (cont’d)

21. 21 8.3 Sources Conversion Example 8.5 Determine I 2 :

22. 22 8.3 Sources Conversion Example 8.5 - solution Convert the current source to a voltage source Note the polarity

23. 23 8.3 Sources Conversion Example 8.5 – solution (cont’d) Reconnect the voltage source E 2 and its resistance R 2 :