1. THEVENIN’S & NORTON’S THEOREM AND MAXIMUM POWER TRANSFER THEOREM
EXPERIMENT 4
THEVENIN’S & NORTON’S THEOREM AND MAXIMUM POWER TRANSFER THEOREM

2. PART A - THEVENIN

3. Construct the circuit in Fig 4.1.
Measure the resistance of each resistor. Record these values in Table 4.1 Select RL as the resistor where it is proposed to determine the current value
Construct the circuit in Fig 4.1.
Table 4.1
Measured values V1 R1 R2 R3 R4 R5 RL

5. Remove resistor RL from the network.
Turn on the supply. Measure the voltage between the points A and D of the network. This is the Thevenin’s voltage. Record the value in Table 4.2
Table 4.2
Measured values
Theoretical values
Thevenin’s
resistance
voltage
current in RL

6. PART B - NORTON

7. Construct the circuit as shown in Fig. 4.1. Do not turn on the supply
Remove resistor RL from the network. RL is selected as the resistor where it is proposed to determine the current value.
Turn on the supply. Read the current shown by the ammeter between terminals A and D. This is Norton’s current, IN. Record its value in Table 4.3.

8. Table 4.2
Measured values
Theoretical values
Thevenin’s
resistance
voltage
current in RL
Table 4.3
Measured values
Theoretical values
Norton’s
Resistance
current
current in RL
resistance

9. PART A - THEVENIN

10. Switch off the power supply
Switch off the power supply. Replace the power supply V1 with a short circuit.
Measure the resistance between terminals A and D. This is the Thevenin’s resistance. Record the value in Table 4.2
Table 4.2
Measured values
Theoretical values
Thevenin’s
resistance
voltage
current in RL

11. PART B - NORTON

12. Switch off the power supply. Replace the supply with a short circuit.
Measure the resistance between terminals A and D. This is Norton’s resistance, record the value in Table 4.3.
Table 4.2
Measured values
Theoretical values
Thevenin’s
resistance
voltage
current in RL
Table 4.3
Measured values
Theoretical values
Norton’s
Resistance
current
current in RL
resistance
Conclusion: RTH = RN

13. PART A - THEVENIN

14. Place back the resistor RL in circuit with an ammeter is connected between terminals A and B or C and D.
Remove the short circuit connection and place back the supply in the circuit.
Turn on the supply. Read and record the current value flowing in the resistor RL.
Table 4.2
Measured values
Theoretical values
Thevenin’s
resistance
voltage
current in RL

15. PART B - NORTON

16. Place back the resistance RL in circuit with an ammeter is connected between terminals A and B or C and D.
Place back the power supply in the circuit and remove the short circuit connection.
Read and record the current value flowing in the resistor RL.
Table 4.2
Measured values
Theoretical values
Thevenin’s
resistance
voltage
current in RL
 619.6 Ω V
4.072 mA
Table 4.3
Measured values
Theoretical values
Norton’s
Resistance
current
current in RL
resistance
  619.6 Ω
5.255 mA 
 4.072 mA

17. PART C – MAXIMUM POWER TRANSFER

18. I Set up the circuit as shown in Fig. 4.2. A C D = GND B
Apply 10V DC from the DC power supply.  Vth = 10 V
No connection RL
Connect to GND
Connect to DMM (-ve) = node C

19. Use the resistor, Rth = 5kΩ
Vary the load rheostat RL from 0 Ω to 10 kΩ.
Measure the voltages VL and I. Take 11 sets of reading.
Record all result in Table 4.4.
Connect to DMM to measure the resistance

20. 0kΩ, 1kΩ, 2kΩ, 3kΩ, 4kΩ, 5kΩ, 6kΩ, 7kΩ, 8kΩ, 9kΩ, 10kΩ
No.
VTH
VL (V)
I (mA)
PIN = VTH I
POUT = VL I
Loss = PIN  POUT %η
%VR
RL = VL / I 1
10 V  2 3 4 5 6 7 8 9 10 11
%η = ( Pout / Pin ) x 100 %
%VR = ( RTH / RL) x 100 %