THEVENIN’S THEOREM

1. THEVENIN’S THEOREM • Thevenins Theorem states that "Any linear circuit containing several voltages and resistances can be replaced by just a Single Voltage in series with a Single Resistor".

2. 4  6  5  2  20 V For example, refer to the circuit Find IL THEVENIN’S THEOREM I1 I2 IL

3. 4  6  A A 2  5  20 V B B Step 1 : Open circuit of 2Ω resistor Open circuit

4. Step 2 : Find the Thevenin voltage, VTH at A - B • Thevenin voltage is the voltage across the terminals A and B is equal to the amount of algebra, which fell on the resistor voltage at 4Ω and 5Ω. • To find the voltage dropped on both the resistor, is in looking to further advance the Ohm's law using the current multiplied by resistance (IR). • In addition the voltage drop on both the resistor can also be found by using the following voltage divider.

5. 4  6  A 5  20 V B Calculation of VTH • VTH Voltage drop across • 4 dan5  = (4  + 5 ) x 20 V (4  + 5 ) + 6  = 12V

6. 4  6  A 5  B Step 3 : Find the Thevenin Resistance, RTH – short circuit the power supply. RTH Short circuit the power supplies and find the Theveninresistance is read at the terminal A and B RTH = 6x9 (6+9) = 54 / 15 = 3.6Ω

7. Step 4 : Draw the Thevenin Equivalent circuit RTH =3.6Ω ITH VTH = 12V RL = 2Ω ITH = IL = VTH / (RTH+RL) = 12 / (3.6+2) = 2.143 Amp ITH is the current through resistor 2Ω = IL is required in the original question.

8. 10  20 V 20  15  Exercises ; Refer to the circuit below, find I3 that flowing through 15Ω I1 I3 I2

9. 10  20  15  20V Calculation ; Step 1: Open circuit the 15 

10. 10  20  20V From the circuit ; Step 2 A VTH B Find VTH = Voltage drop at 20Ω (using voltage divider) VTH = 20Ω x 20 V = 13.33 V (10Ω + 20Ω)

11. 10  20  • Step 3 • RTH • Short circuit supplies and find RTH ( perintang 10 selaridenganperintang20  ) • RTH = 10 // 20 • = 10x20/(10+20) • = 6.67 

12. 6.67  15  13.33 V Step 4 Draw the Theveninequvalent circuit ITH ITH = I3 = VTH /(RTH+RL) = 13.33 / (6.67+15)) = 0.615 A

13. Exercise ;