1. Network theorems
Week of 8th September 2008

2. Questions till the 1st In-sem exam

3. Thevenin’s Theorem
Used to replace any linear circuit with an equivalent voltage source called VTH and an equivalent resistance called RTH

4. Thevenin Example Original Circuit

5. Thevenin’s theorem can be used to replace any
linear circuit with an equivalent voltage source
called VTH and an equivalent resistance called RTH.
6 kW
4 kW
VTH
72 V RL
3 kW
RTH
Calculate or measure
Thevenin’s resistance (RTH)
Remove the source.
Remove the load.
Calculate or measure VTH across the open terminals.

6. Thevenin’s Voltage

7. Original circuit Thevenin equivalent circuit
6 kW
4 kW
Original
circuit
72 V RL
3 kW
6 kW (RTH)
Thevenin
equivalent circuit RL
24 V (VTH)

8. Norton’s Theorem
Used to replace any linear circuit with an equivalent current source called IN and an equivalent resistance called RN

9. Norton’s Current
IN = 4 mA
RN = 6 KW

10. A Thevenin equivalent circuit The Norton dual
6 kW (RTH)
A Thevenin
equivalent circuit RL
24 V (VTH)
VTH
Circuit Conversion
RN = RTH
IN =
RTH
6 kW (RN) RL
4 mA (IN)
The Norton
dual

11. Superposition Theorem

12. Circuit Theorems
Refer Chapter 5 from book of Dorf and/or Chapter 1 of Malvino.
Chapter 5 of Dorf is much more comprehensive, with lots of examples and exercises.

13. Two-loop problem – Superposition theorem – Current through R2

14. Thevenin’s circuit application to two loop problem – Calculate current through R2

15. Norton’s theorem – Current through R2

16. Electronics in real life ( a small detour! )

17. Name some applications where you have seen electronic being used

18. Electrical Engineering
Telecommunications ( Telegraph (Morse code), Telephone)
Amplifiers
Electrical Power Systems

19. Transducers and Sensors
Potentiometer
Temperature sensor
Switches and their types – ( Multisim model)