1. Thevenin’s Theorem By: Engr.Irshad Raheem Memon
PRACTICAL # 06
Thevenin’s Theorem
By: Engr.Irshad Raheem Memon

2. OBJECTIVE
Objective of this practical is to learn about Thevenin’s Theorem; and how this theorem is used to convert a complex resistive DC circuit into thevenin equivalent circuit

3. What is Thevenin’s Theorem
Thevenin’s theorem provides a method for simplifying any two terminal complex resistive DC circuit to an standard equivalent form. Thevenin’s equivalent circuit consists of an equivalent voltage source and a resistor in series

4. Thevenin equivalent circuit is shown in figure 01.

5. Description Continued…
Thevenin equivalent voltage is the open circuit (no load) voltage between two output terminals A& B in a circuit. Thevenin equivalent resistance is the total resistance appearing between two output terminals A & B in a given circuit with all sources replaced by their internal resistances.

6. Continued…
Thevenin’s equivalent circuit acts same in terms of output voltage and current as visualized in figure 02.

7. Steps for applying Thevenin’s theorem:
Step 01: Open the two terminals (remove any load) between which you want to find the Thevenin equivalent circuit
Step 02: Determine the voltage (Vth) across the two open terminals
Step 03: Determine the resistance (Rth) between the two open terminals with all sources replaced with their internal resistances.
Step 04: Connect Vth and Rth in series to produce the complete Thevenin equivalent circuit for the original circuit.
Step 05: Replace the load removed in Step 01 across the terminals of the Thevenin equivalent circuit. You can now calculate the load current and load voltage using only Ohm’s law. They have the same value as the load current and load voltage in original circuit.

8. Coming Towards Objective Now

9. REQUIRED APPARATUS Multism Software Resistors Bread board Multimeter
DC voltage source
Connecting wire etc

10. PROCEDURE
Realize the circuit on breadboard as shown in figure 01(a)Find out voltage across and current through terminals A & B in original circuit. Then convert this circuit into Thevenin equivalent circuit by following the steps of Thevenin’s theorem. Vth and Rth for original circuit can be found as given in figure 03.

11. STEP 01
Open the two terminals (remove any load) between which you want to find the Thevenin equivalent circuit

12. STEP 01 Circuit on MULTISM

13. STEP 02
Determine the voltage (Vth) across the two open terminals

14. STEP 02 Circuit on MULTISM

15. STEP 03
Determine the resistance (Rth) between the two open terminals with all sources replaced with their internal resistances.

16. STEP3 Circuit on MULTISM

17. STEP 04
Connect Vth and Rth in series to produce the complete Thevenin equivalent circuit for the original circuit

18. STEP 05
Replace the load removed in Step 01 across the terminals of the Thevenin equivalent circuit.You can now calculate the load current and load voltage using only Ohm’s law. They have the same value as the load current and load voltage in original circuit
Now To Prove Results. We have to prove that Output Voltage and Current of Original Circuit must beEqual to Thevenin Output Voltage & Current

19. STEP 05 RESULTS
So we see from Results that Output Voltage and Current of Original Circuit is Equal to Thevenin Output Voltage & Current

20. Prove All Results Above Manually

21. Observation:-
Value of current through and voltage across terminals A & B in both original and thevenin equivalent circuit is same.

22. ANY QUERY