Name: Tam Kin Cheung
Student ID#: 51075869
Lab Section: L04


Lab06: Theveninˇ¦s Equivalent Circuit and Maximum Power Transfer Theorem




Introduction:

	This experiment is about Theveninˇ¦s Equivalent of two-terminal circuit composed of resistors and voltage sources only. Through studying Theveminˇ¦s Equivalent circuit, maximum power transfer theorem can be applied and the condition also can be conducted.

Procedure and Data:

Experiment 1: To determine the Theveninˇ¦s equivalent of a given circuit









a.  Procedure

	At the beginning, a circuit should be connected as Figure 1. The voltage across a-b should be measured by DMM. DC power supply is disconnected at first, and Thevenin resistance should be measured by DMM. Finally, calculated results and measured results are compared.

b.	Data and Result

Original R (kŁ[)	Measured R (kŁ[)
2	2.01
3	2.96
10	9.92
10	9.86
Table 1  Measured resistance of resistors used in experiment

	Calculated results	Measured results
  (V)	0.5	0.456
  (kŁ[)	6.2	6.14
Table 2  Calculated and measured results in experiment

	Two results are close to each other, so it proved the experiment is consistent.

Experiment 2: To determine the condition of maximum power transfer for a given circuit.

a.	Procedure

Firstly, the circuit should be reconnected as Figure 1. A variable resistor is connected at terminal a-b, and is adjusted the resistance of this resistor at different values. The resistance should be increased from 0kŁ[ to 10kŁ[, and record voltage across terminal a-b at different resistance. Plotting a graph by these data, the condition of maximum power transfer can be conducted.

b.	Data and Results

Resistance (kŁ[)	Voltage (mV)	Power (ŁgW)
0.501	35	2.44511
1.05	69.2	4.56061
1.511	93.4	5.773369
2.051	117.8	6.76589
2.513	137	7.468762
3.11	159.3	8.159643
3.44	170.3	8.43084
4.04	188	8.748515
4.47	199.8	8.930658
4.91	211.8	9.136301
5.47	223.4	9.123868
6.01	234.1	9.118604
6.15	236.5	9.094675
6.17	238.2	9.195987
6.24	239	9.154006
6.53	244.3	9.139738
6.99	252	9.084979
7.55	261.2	9.036482
7.99	267.8	8.975825
8.48	274.4	8.87917
9.03	282	8.806645
9.48	288.1	8.755444
10.02	293.7	8.608751
Table 3  The data and result in experiment 2

 
Figure 2  Power delivered to the variable resistor

 
Figure 3  Position at maximum power transfer

 ,  
 

	The result in this experiment is consistent to the maximum power transfer theorem.

Discussion:

1.	It means that the output of the circuit should be linear transform of the input of the circuit. No other component changes the phase between input and output.

2.	In maximum power transfer theorem,
 
Figure 4  Circuit used for maximum power transfer theorem

The power dissipated ( ) of  =   =   
 	The condition of maximum power   is minimum
 
  = 0
 
It proved that the condition of maximum power transfer theorem is  .

3.& 4. 
No. The peak is not similar.
New :
 
Therefore, the peak should be changed following the value of  

5. 





Figure 5  A sample circuit converted into theveninˇ¦s circuit

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