Questions

Question 1

Animation: Applying Thevenin’s theorem

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The following animation shows the steps involved in ”Thevenizing” a circuit.

1

RloadR1

R2

R3

18 V

10 kΩ

12 kΩ

14 kΩ

2

RloadR1

R2

R3

18 V

10 kΩ

12 kΩ

14 kΩ

This is our original circuit:

3

RloadR1

R2

R3

18 V

10 kΩ

12 kΩ

14 kΩ

We may use Thevenin’s theoremto simplify this portion of the circuit . . .

4

Rload

We may use Thevenin’s theoremto simplify this portion of the circuit . . .

R1

R2

R3

18 V

10 kΩ

12 kΩ

14 kΩ

5

Rload

We may use Thevenin’s theoremto simplify this portion of the circuit . . .

R1

R2

R3

18 V

10 kΩ

12 kΩ

14 kΩ

6

Rload

We may use Thevenin’s theoremto simplify this portion of the circuit . . .

R1

R2

R3

18 V

10 kΩ

12 kΩ

14 kΩ

7

RloadR1

R2

R3

18 V

10 kΩ

12 kΩ

14 kΩ

8

RloadR1

R2

R3

18 V

10 kΩ

12 kΩ

14 kΩ

To this Thevenin equivalent circuit . . .

9

RloadR1

R2

R3

18 V

10 kΩ

12 kΩ

14 kΩ

To this Thevenin equivalent circuit . . .

VTH

RTH

10

RloadR1

R2

R3

18 V

10 kΩ

12 kΩ

14 kΩ

VTH

RTH

. . . to which we may attachthe same load and analyze.

11

RloadR1

R2

R3

18 V

10 kΩ

12 kΩ

14 kΩ

VTH

RTH

. . . to which we may attachthe same load and analyze.

Rload

12

RloadR1

R2

R3

18 V

10 kΩ

12 kΩ

14 kΩ

VTH

RTH

. . . to which we may attachthe same load and analyze.

Rload

13

RloadR1

R2

R3

18 V

10 kΩ

12 kΩ

14 kΩ

VTH

RTH

. . . to which we may attachthe same load and analyze.

Rload

14

RloadR1

R2

R3

18 V

10 kΩ

12 kΩ

14 kΩ

VTH

RTH

. . . to which we may attachthe same load and analyze.

Rload

15

RloadR1

R2

R3

18 V

10 kΩ

12 kΩ

14 kΩ

VTH

RTH

Rload

16

RloadR1

R2

R3

18 V

10 kΩ

12 kΩ

14 kΩ

VTH

RTH

Rload

the load resistor.First we disconnect

17

RloadR1

R2

R3

18 V

10 kΩ

12 kΩ

14 kΩ

VTH

RTH

the load resistor.First we disconnect

18

Rload

R1

R2

R3

18 V

10 kΩ

12 kΩ

14 kΩ

VTH

RTH

the load resistor.First we disconnect

19

Rload

R1

R2

R3

18 V

10 kΩ

12 kΩ

14 kΩ

VTH

RTH

the load resistor.First we disconnect

20

Rload

R1

R2

R3

18 V

10 kΩ

12 kΩ

14 kΩ

VTH

RTH

21

Rload

R1

R2

R3

18 V

10 kΩ

12 kΩ

14 kΩ

VTH

RTH

Then we calculate howmuch voltage appearsacross the open load

terminals.

22

Rload

R1

R2

R3

18 V

10 kΩ

12 kΩ

14 kΩ

VTH

RTH

Then we calculate howmuch voltage appearsacross the open load

terminals.+

V-

23

Rload

R1

R2

R3

18 V

10 kΩ

12 kΩ

14 kΩ

VTH

RTH

Then we calculate howmuch voltage appearsacross the open load

terminals.+

V-

24

Rload

R1

R2

R3

18 V

10 kΩ

12 kΩ

14 kΩ

VTH

RTH

Then we calculate howmuch voltage appearsacross the open load

terminals.+

V- (18 volts)

10 kΩ

(14 kΩ + 12 kΩ + 10 kΩ)

25

Rload

R1

R2

R3

18 V

10 kΩ

12 kΩ

14 kΩ

VTH

RTH

Then we calculate howmuch voltage appearsacross the open load

terminals.+

V- (18 volts)

10 kΩ

(14 kΩ + 12 kΩ + 10 kΩ)

= 5 volts

26

Rload

R1

R2

R3

18 V

10 kΩ

12 kΩ

14 kΩ

VTH

RTH

+V

-5 V

27

Rload

R1

R2

R3

18 V

10 kΩ

12 kΩ

14 kΩ

VTH

RTH

+V

-5 V

This voltage becomesour Thevenin sourcevoltage . . .

28

Rload

R1

R2

R3

18 V

10 kΩ

12 kΩ

14 kΩ

RTH

+V

-5 V

This voltage becomesour Thevenin sourcevoltage . . .

5 V

29

Rload

R1

R2

R3

18 V

10 kΩ

12 kΩ

14 kΩ

RTH

+V

-5 V

This voltage becomesour Thevenin sourcevoltage . . .

5 V. . . in the Thevenin equivalent circuit.

30

Rload

R1

R2

R3

18 V

10 kΩ

12 kΩ

14 kΩ

RTH

5 V

31

Rload

R1

R2

R3

18 V

10 kΩ

12 kΩ

14 kΩ

RTH

5 V

Now we replace each sourcein the original circuit with itsown internal resistance.

32

Rload

R1

R2

R3

18 V

10 kΩ

12 kΩ

14 kΩ

RTH

5 V

Now we replace each sourcein the original circuit with itsown internal resistance.

For voltage sources, thismeans a short-circuit.

33

Rload

R1

R2

R3

18 V

10 kΩ

12 kΩ

14 kΩ

RTH

5 V

Now we replace each sourcein the original circuit with itsown internal resistance.

For voltage sources, thismeans a short-circuit.

34

Rload

R1

R2

R3

18 V

10 kΩ

12 kΩ

14 kΩ

RTH

5 V

Now we replace each sourcein the original circuit with itsown internal resistance.

For voltage sources, thismeans a short-circuit.

35

Rload

R1

R2

R3 10 kΩ

12 kΩ

14 kΩ

RTH

5 V

Now we replace each sourcein the original circuit with itsown internal resistance.

For voltage sources, thismeans a short-circuit.

36

Rload

R1

R2

R3 10 kΩ

12 kΩ

14 kΩ

RTH

5 V

37

Rload

R1

R2

R3 10 kΩ

12 kΩ

14 kΩ

RTH

5 V

resistance across the openload terminals.

. . . and we calculate

38

Rload

R1

R2

R3 10 kΩ

12 kΩ

14 kΩ

RTH

5 V

resistance across the openload terminals.Ω

. . . and we calculate

39

Rload

R1

R2

R3 10 kΩ

12 kΩ

14 kΩ

RTH

5 V

resistance across the openload terminals.Ω

. . . and we calculate

40

Rload

R1

R2

R3 10 kΩ

12 kΩ

14 kΩ

RTH

5 V

resistance across the openload terminals.Ω

. . . and we calculate

(14 kΩ + 12 kΩ) // 10 kΩ

41

Rload

R1

R2

R3 10 kΩ

12 kΩ

14 kΩ

RTH

5 V

resistance across the openload terminals.Ω

. . . and we calculate

(14 kΩ + 12 kΩ) // 10 kΩ= 7.22 kΩ

42

Rload

R1

R2

R3 10 kΩ

12 kΩ

14 kΩ

RTH

5 V

Ω 7.22 kΩ

43

Rload

R1

R2

R3 10 kΩ

12 kΩ

14 kΩ

RTH

5 V

Ω 7.22 kΩ

This resistance becomesour Thevenin source

resistance . . .

44

Rload

R1

R2

R3 10 kΩ

12 kΩ

14 kΩ

5 V

Ω 7.22 kΩ

This resistance becomesour Thevenin source

resistance . . .

7.22 kΩ

45

Rload

R1

R2

R3 10 kΩ

12 kΩ

14 kΩ

5 V

Ω 7.22 kΩ

This resistance becomesour Thevenin source

resistance . . .

7.22 kΩ

. . . in the Thevenin equivalent circuit.

46

Rload

R1

R2

R3 10 kΩ

12 kΩ

14 kΩ

5 V

7.22 kΩ

18 V

47

Rload

R1

R2

R3 10 kΩ

12 kΩ

14 kΩ

5 V

7.22 kΩ

Now that we have an equivalent circuit to

work with, we may insertthe load there to see what

happens!

18 V

48

Rload

R1

R2

R3 10 kΩ

12 kΩ

14 kΩ

5 V

7.22 kΩ

Now that we have an equivalent circuit to

work with, we may insertthe load there to see what

happens!

18 V

49

Rload

R1

R2

R3 10 kΩ

12 kΩ

14 kΩ

5 V

7.22 kΩ

Now that we have an equivalent circuit to

work with, we may insertthe load there to see what

happens!

18 V

50

Rload

R1

R2

R3 10 kΩ

12 kΩ

14 kΩ

5 V

7.22 kΩ

Now that we have an equivalent circuit to

work with, we may insertthe load there to see what

happens!

18 V

51

Rload

R1

R2

R3 10 kΩ

12 kΩ

14 kΩ

5 V

7.22 kΩ

Now that we have an equivalent circuit to

work with, we may insertthe load there to see what

happens!

18 V

52

Rload

R1

R2

R3 10 kΩ

12 kΩ

14 kΩ

5 V

7.22 kΩ

Now that we have an equivalent circuit to

work with, we may insertthe load there to see what

happens!

Calculate:

18 V

53

Rload

R1

R2

R3 10 kΩ

12 kΩ

14 kΩ

5 V

7.22 kΩ

Now that we have an equivalent circuit to

work with, we may insertthe load there to see what

happens!

Calculate:

Vload

18 V

54

Rload

R1

R2

R3 10 kΩ

12 kΩ

14 kΩ

5 V

7.22 kΩ

Now that we have an equivalent circuit to

work with, we may insertthe load there to see what

happens!

Calculate:

Vload

Iload

18 V

55

Rload

R1

R2

R3 10 kΩ

12 kΩ

14 kΩ

5 V

7.22 kΩ

Now that we have an equivalent circuit to

work with, we may insertthe load there to see what

happens!

Calculate:

Vload

Iload

Pload

18 V

56

Rload

R1

R2

R3 10 kΩ

12 kΩ

14 kΩ

5 V

7.22 kΩ

Calculate:

Vload

Iload

Pload

18 V

57

Rload

R1

R2

R3 10 kΩ

12 kΩ

14 kΩ

5 V

7.22 kΩ

Calculate:

Vload

Iload

Pload

18 VThese load calculations willreflect what happens in theoriginal circuit!

58

Rload

R1

R2

R3 10 kΩ

12 kΩ

14 kΩ

5 V

7.22 kΩ

Calculate:

Vload

Iload

Pload

18 VThese load calculations willreflect what happens in theoriginal circuit!

Rload

59

Rload

R1

R2

R3 10 kΩ

12 kΩ

14 kΩ

5 V

7.22 kΩ

Calculate:

Vload

Iload

Pload

18 VThese load calculations willreflect what happens in theoriginal circuit!

RloadVload

(same)

60

Rload

R1

R2

R3 10 kΩ

12 kΩ

14 kΩ

5 V

7.22 kΩ

Calculate:

Vload

Iload

Pload

18 VThese load calculations willreflect what happens in theoriginal circuit!

RloadVload

(same)

Iload

61

Rload

R1

R2

R3 10 kΩ

12 kΩ

14 kΩ

5 V

7.22 kΩ

Calculate:

Vload

Iload

Pload

18 VThese load calculations willreflect what happens in theoriginal circuit!

RloadVload

(same)

Iload

Pload

62

Rload

R1

R2

R3 10 kΩ

12 kΩ

14 kΩ

5 V

7.22 kΩ

Calculate:

Vload

Iload

Pload

18 VThese load calculations willreflect what happens in theoriginal circuit!

RloadVload

Iload

Pload

63

Rload

R1

R2

R3 10 kΩ

12 kΩ

14 kΩ

5 V

7.22 kΩ Vload

Iload

Pload

18 V

Rload

Vload

Iload

Pload

64

Rload

R1

R2

R3 10 kΩ

12 kΩ

14 kΩ

5 V

7.22 kΩ Vload

Iload

Pload

18 V

Rload

Vload

Iload

Pload

65

Rload

R1

R2

R3 10 kΩ

12 kΩ

14 kΩ

5 V

7.22 kΩ Vload

Iload

Pload

18 V

Rload

Vload

Iload

Pload

The load cannot ‘‘tell’’any difference between the

Thevenin equivalent circuit.original circuit and the

file 03261

66

Answers

Answer 1

Nothing to note here.

67

Notes

Notes 1

The purpose of this animation is to let students see how Thevenin’s theorem may be applied to the

simplification of a resistor network.

68